chore: bring back deprecation warning

frontend/src/component/strategies/StrategiesList/StrategiesList.tsx

@@ -92,6 +92,25 @@ const Title: FC<{
     </StyledTitle>
 );
 
+const StrategyDeprecationWarning = () => (
+    <Alert severity='warning' sx={{ mb: 2 }}>
+        Custom strategies are deprecated and may be removed in a future major
+        version. We recommend not using custom strategies going forward and
+        instead using the gradual rollout strategy with{' '}
+        <Link
+            href={
+                'https://docs.getunleash.io/reference/activation-strategies#constraints'
+            }
+            target='_blank'
+            rel='noopener noreferrer'
+        >
+            constraints
+        </Link>
+        . If you have a need for custom strategies that you cannot support with
+        constraints, please reach out to us.
+    </Alert>
+);
+
 const RecommendationAlert = () => (
     <Alert severity='info' sx={{ mb: 2 }}>
         We recommend using gradual rollout. You can customize it with{' '}
@@ -531,6 +550,7 @@ export const StrategiesList = () => {
                         <span>Custom strategies</span>
                         <AddStrategyButton />
                     </StyledSubtitle>
+                    <StrategyDeprecationWarning />
                     <Table {...customGetTableProps()}>
                         <SortableTableHeader
                             headerGroups={customHeaderGroups}