Arknights: Endfield Friends are friends you add in-game. PlayStation™Network Friends are friends from the PSN account.
Actions on friends on iOS, Android, or PC do not affect PlayStation™Network friend status.
Blocking a friend of your PSN account removes them from both PlayStation™Network Friends List and Arknights: Endfield Friends List. The friend remains visible when you play on other platforms.
Removing a friend from your PSN account only removes them from the PlayStation™Network Friends List. The Arknights: Endfield Friends List remains unchanged.