Same here. Have had iPhones since 3GS and never had an issue. Last phone before iPhone Pro Max 12 was an iPhone X which is the best phone i've ever had. Never had any issues with bluetooth, now it's a nightmare. Stuttering audio in my earpods, disconnect, reconnect and it works fine for a few minutes than stuttering again. It works best in my Mercedes bluetooth where the problem is more rare but they are there too. I've tried everything that's listed, resetting network settings and all... same problem. The only thing left is to start up the phone without using a backup, but that is insane. I gave my wife my iPhone X but i'm thinking of swapping with her since i use my bluetooth (and phone in work) a lot and she doesnt use bluetooth. It's not worth these issues, this has to be hardware related.

i have had problems on my 12 max pro since I bought it, never had issues with my iPhone X before that. Calls cut My EarPods several times a day and I had so much trouble that i went back to cable. I solved the problem by accident a couple month ago when my Apple Watch series 2 died after many years of use, and I got a series 6 watch. After that all my Bluetooth issues were solved (I did both reinstall the phone, network reset and all recommendations before, I even sent my phone in for service but apple said there was nothing wrong with it). Obviously in my case, there was something wrong affected by my Apple Watch series 2.