I applied the available Android 12 update to my A51, and immediately was unable to end calls. Even if I clicked the end call button repeatedly, either on the call screen or in the pull down menu, the call duration clock kept going.
I did a factory reset, which fixed things for a week, and then it started again. I had hoped the reset would allow me to go with Android 11 but it automatically downloaded 12 again I guess.
I just tried to make a call and the phone kept the ringing out tone still going even after my call was picked up so I heard "Good morni*RING* this is*Ring*" as if it was still dialing.
Sometimes it takes up to 30 seconds after choosing to end the call before the hanging up sound plays and the timer ends the call, and people can still hear me I think after I've ended the call.
My phone has taken to randomly restarting as it did before the factory reset (but after the update) regardless of if only one app is in use and how cool the phone is.
If it is relevant, I'm in Germany, running my phone in English and have attached the software info. I can provide any more data if needed, but not being able to