app/Http/Controllers/Admin/UserManagementController.php

@@ -26,9 +26,9 @@ class UserManagementController extends Controller
     public function update(UpdateUserAdminStatusRequest $request, User $user): RedirectResponse
     {
         $validated = $request->validated();
-
-        $user->is_admin = $validated['is_admin'];
-        $user->save();
+        $user->forceFill([
+            'is_admin' => Arr::get($validated, 'is_admin'),
+        ])->save();
 
         $status = $user->is_admin
             ? "{$user->name} now has admin access."

app/Http/Requests/UpdateTeamMembersRequest.php

@@ -25,7 +25,7 @@ class UpdateTeamMembersRequest extends FormRequest
     {
         return [
             'user_ids' => ['nullable', 'array'],
-            'user_ids.*' => ['integer', Rule::exists('users', 'id')],
+            'user_ids.*' => ['integer', 'distinct', Rule::exists('users', 'id')],
         ];
     }