diff --git a/src/lib/openapi/spec/user-schema.test.ts b/src/lib/openapi/spec/user-schema.test.ts
index acf4c4d32d..946902e68e 100644
--- a/src/lib/openapi/spec/user-schema.test.ts
+++ b/src/lib/openapi/spec/user-schema.test.ts
@@ -3,7 +3,6 @@ import type { UserSchema } from './user-schema.js';
 
 test('userSchema', () => {
     const data: UserSchema = {
-        isAPI: false,
         id: 1,
         username: 'admin',
         imageUrl: 'avatar',
diff --git a/src/lib/openapi/spec/user-schema.ts b/src/lib/openapi/spec/user-schema.ts
index dbd8bef37a..e7371638e8 100644
--- a/src/lib/openapi/spec/user-schema.ts
+++ b/src/lib/openapi/spec/user-schema.ts
@@ -13,13 +13,6 @@ export const userSchema = {
             type: 'integer',
             example: 123,
         },
-        isAPI: {
-            description:
-                'Deprecated in v5. Used internally to know which operations the user should be allowed to perform',
-            type: 'boolean',
-            example: true,
-            deprecated: true,
-        },
         name: {
             description: 'Name of the user',
             type: 'string',
diff --git a/src/lib/openapi/validate.ts b/src/lib/openapi/validate.ts
index e7b5c1d4a3..367beac1cc 100644
--- a/src/lib/openapi/validate.ts
+++ b/src/lib/openapi/validate.ts
@@ -1,5 +1,5 @@
 import type { ErrorObject } from 'ajv';
-import Ajv from 'ajv';
+import { Ajv } from 'ajv';
 import { type SchemaId, schemas } from './index.js';
 import { omitKeys } from '../util/index.js';
 import { fromOpenApiValidationErrors } from '../error/bad-data-error.js';
@@ -8,7 +8,7 @@ export interface ISchemaValidationErrors<S = SchemaId> {
     schema: S;
     errors: ErrorObject[];
 }
-// @ts-expect-error: Does not expose constructor
+
 const ajv = new Ajv({
     schemas: Object.values(schemas).map((schema) =>
         omitKeys(schema, 'components'),
@@ -34,9 +34,9 @@ export const addAjvSchema = (schemaObjects: any[]): any => {
 };
 
 export const validateSchema = <S = SchemaId>(
-    schema: S,
+    schema: SchemaId,
     data: unknown,
-): ISchemaValidationErrors<S> | undefined => {
+): ISchemaValidationErrors<SchemaId> | undefined => {
     if (!ajv.validate(schema, data)) {
         return {
             schema,
@@ -46,7 +46,7 @@ export const validateSchema = <S = SchemaId>(
 };
 
 export const throwOnInvalidSchema = <S = SchemaId>(
-    schema: S,
+    schema: SchemaId,
     data: object,
 ): void => {
     const validationErrors = validateSchema(schema, data);
diff --git a/src/lib/routes/admin-api/user-admin.ts b/src/lib/routes/admin-api/user-admin.ts
index a8c27dfb92..5000cb18d3 100644
--- a/src/lib/routes/admin-api/user-admin.ts
+++ b/src/lib/routes/admin-api/user-admin.ts
@@ -495,7 +495,7 @@ export default class UserAdminController extends Controller {
         const rootRoles = await this.accessService.getRootRoles();
         const inviteLinks = await this.resetTokenService.getActiveInvitations();
 
-        const usersWithInviteLinks = users.map((user) => {
+        const usersWithInviteLinks = users.map(({ isAPI, ...user }) => {
             const inviteLink = inviteLinks[user.id] || '';
             return { ...user, inviteLink };
         });
@@ -533,7 +533,7 @@ export default class UserAdminController extends Controller {
             200,
             res,
             usersSearchSchema.$id,
-            serializeDates(users),
+            serializeDates(users.map(({ isAPI, ...u }) => u)),
         );
     }
 
@@ -580,7 +580,7 @@ export default class UserAdminController extends Controller {
         res: Response<UserSchema>,
     ): Promise<void> {
         const { id } = req.params;
-        const user = await this.userService.getUser(id);
+        const { isAPI, ...user } = await this.userService.getUser(id);
 
         this.openApiService.respondWithValidation(
             200,
@@ -621,8 +621,9 @@ export default class UserAdminController extends Controller {
             ? await this.userService.sendWelcomeEmail(createdUser, inviteLink)
             : false;
 
+        const { isAPI, ...user } = createdUser;
         const responseData: CreateUserResponseSchema = {
-            ...serializeDates(createdUser),
+            ...serializeDates(user),
             inviteLink,
             emailSent,
             rootRole: normalizedRootRole,
@@ -654,7 +655,7 @@ export default class UserAdminController extends Controller {
             ? Number(rootRole)
             : (rootRole as RoleName);
 
-        const updateUser = await this.userService.updateUser(
+        const { isAPI, ...updateUser } = await this.userService.updateUser(
             {
                 id,
                 name,
@@ -733,7 +734,9 @@ export default class UserAdminController extends Controller {
         res: Response<UserAccessOverviewSchema>,
     ): Promise<void> {
         const { project, environment } = req.query;
-        const user = await this.userService.getUser(req.params.id);
+        const { isAPI, ...user } = await this.userService.getUser(
+            req.params.id,
+        );
         const rootRole = await this.accessService.getRootRoleForUser(user.id);
         let projectRoles: IRoleWithPermissions[] = [];
         if (project) {
diff --git a/src/lib/routes/admin-api/user/user.ts b/src/lib/routes/admin-api/user/user.ts
index b286a72db6..736e7c5834 100644
--- a/src/lib/routes/admin-api/user/user.ts
+++ b/src/lib/routes/admin-api/user/user.ts
@@ -222,8 +222,9 @@ class UserController extends Controller {
             await this.userFeedbackService.getAllUserFeedback(user);
         const splash = await this.userSplashService.getAllUserSplashes(user);
 
+        const { isAPI, ...responseUser } = user;
         const responseData: MeSchema = {
-            user: serializeDates(user),
+            user: serializeDates(responseUser),
             permissions,
             feedback: serializeDates(feedback),
             splash,
diff --git a/src/lib/routes/auth/simple-password-provider.ts b/src/lib/routes/auth/simple-password-provider.ts
index 8e40a87695..0a77020f5b 100644
--- a/src/lib/routes/auth/simple-password-provider.ts
+++ b/src/lib/routes/auth/simple-password-provider.ts
@@ -62,10 +62,14 @@ export class SimplePasswordProvider extends Controller {
         const { username, password } = req.body;
         const userAgent = req.get('user-agent');
 
-        const user = await this.userService.loginUser(username, password, {
-            userAgent,
-            ip: req.ip,
-        });
+        const { isAPI, ...user } = await this.userService.loginUser(
+            username,
+            password,
+            {
+                userAgent,
+                ip: req.ip,
+            },
+        );
         req.session.user = user;
         this.openApiService.respondWithValidation(
             200,
diff --git a/src/lib/routes/public-invite.ts b/src/lib/routes/public-invite.ts
index 973505e16b..28e1acc1b8 100644
--- a/src/lib/routes/public-invite.ts
+++ b/src/lib/routes/public-invite.ts
@@ -108,11 +108,12 @@ export class PublicInviteController extends Controller {
             res.status(400).end();
             return;
         }
-        const user = await this.publicSignupTokenService.addTokenUser(
-            token,
-            req.body,
-            req.audit,
-        );
+        const { isAPI, ...user } =
+            await this.publicSignupTokenService.addTokenUser(
+                token,
+                req.body,
+                req.audit,
+            );
         this.openApiService.respondWithValidation(
             201,
             res,
diff --git a/src/lib/services/openapi-service.ts b/src/lib/services/openapi-service.ts
index 66fc7ee6b0..788d861bbc 100644
--- a/src/lib/services/openapi-service.ts
+++ b/src/lib/services/openapi-service.ts
@@ -96,7 +96,7 @@ export class OpenApiService {
     respondWithValidation<T, S = SchemaId>(
         status: number,
         res: Response<T>,
-        schema: S,
+        schema: SchemaId,
         data: T,
         headers: { [header: string]: string } = {},
     ): void {
@@ -104,8 +104,8 @@ export class OpenApiService {
 
         if (errors) {
             this.logger.debug(
-                'Invalid response:',
-                JSON.stringify(errors, null, 4),
+                `Invalid response for ${res.req?.originalUrl || ''}:`,
+                errors,
             );
             if (this.flagResolver.isEnabled('strictSchemaValidation')) {
                 throw new Error(JSON.stringify(errors, null, 4));