ios 15.3.1 - A hot mess?

I've had ios since my iphone 3. Its always been reliable, never too buggy. 15.3.1 feels like I'm a beta tester.

I updated direct to 15.3.1 from latest version of ios 14 on my iphone 12, since then I have no end of trouble, restarts & issues.

Just this week I have had the following

Unable to use mobile data 4G or 5G. I have to restart the phone. Sometimes I can get away with just moving between airplane mode, but it always fails after a little time. Not app dependant, it just stops working.

When I make a call, if I put it to my ear, the screen goes black but I cant get back to the phone screen, it shows a see through version of the notifications on my lock screen, like I half swiped up on the screen but I haven't. It does it all the time so I cant hang up, I'm reliant on the other caller to hang up. Then I can use the phone again with a swipe up.

Touch on the screen also seems less responsive and acts weird. This phone has no physical damage and has never been dropped. Some gestures that worked 4 days ago only work haphazardly now.

Pulling up an image in messages freezes the screen and I have to swipe up to remove it so I can go back into the messages app.

This is junk and from Apple I expect this stuff not to happen, this device was perfect 4 days ago on ios 14, ios 15.3.1 is junk.