How to fix ringer volume not decreasing when picking up locked iPhone 16 Pro while ringing?

My phone is iPhone 16 pro. I am facing an interesting problem.

If I receive a call while my phone's screen is on, when I pick up my phone, the ringer volume is reduced (I want it to be exactly like this).. BUT when I pick up my phone while my phone is locked and the screen is closed, the ringer volume does not decrease (and Face ID does not unlock the screen). If I swipe up on the screen, the screen is unlocked, but the ringer is completely silent.. It's interesting bug...

What was done for the problem:

Apple support remotely accessed my phone and checked the necessary settings and everything was normal... (they reached me by writing and calling) Event ID: 10*****16

I reset the phone and it still didn't work...

I switched from version 18.3 to 18.3.1 and it still didn't work...

I'm waiting for a solution... Thank you

[Edited by Moderator]