How do I fix FaceTime video call issues on my iPhone 13 Pro?

I’m a 13pro user.

after I updated to 18.4, I have issues with my facetime video call.

1. I am unable to make facetime video call. Tried restarting, but it happened again. But when others (15pro user) make call, it worked.
2. the PIP doesn’t work either. When the phone is still ringing, the PIP doesn’t work. When the call is connected, it did not show the caller real video, just their icon.

Anyone have any suggestion?

[Re-Titled by Moderator]