ACF Update_field() update the field but changes are not seen in backend or rest api

Ok got it, for user field actually one has to add “user_” before the id for it to work. So in my case:

update_field( $cover_custom_field_key, $cover_id, "user_2" ); 

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)