I spoke with Apple Tier 2 support yesterday for a while. She had me reset my network settings. It actually seemed to fix the issue but only briefly. She then asked me to back-up of my phone and try "Reset All Settings". It has been about 20 hours since I did this and it's been 99% better. I had one instance where my left aid lost connection & reconnected three times in a row. Outside of that, I've had two phone calls and I've listened to podcasts off and on without any issues. I have not been able to do any of this since getting my new iPhone 12 Pro.
Please make sure your iCloud backup is up-to-date or plug into your computer and get an iTunes backup before you do this. Note, it's not pleasant, all my settings like wallpaper, ringtones, face id, apple pay cards, passcode, etc. are all gone. BUT, if some rogue setting somewhere it causing this issue, it's potentially gone now and appears to be worth the trouble so far.
To try this, go to Settings > General > Reset > "Reset All Settings"
Remember to reenter your WiFi password when you get back up and running.
I'm curious if anyone else having issues will try this and if they experience positive results. I've asked if my ticket could remain open for a few days as I continue to use my phone to see if the issue resurfaces.