I understand that most people have no problems, but there is still a minority of users with these disconnection problems.
The software is up to date on both iPhone and all the Macs I use the Airpods with.
The Airpods' firmware is up to date.
I removed and re-added them to my account multiple times.
Apple replaced them under warranty (the pods, not the case) about 6 months ago as stated above. They said they were defective. Nothing changed, experiencing the same exact problems with the new pair.
I recently started using them without automatic ear detection. Seems better, but marginally, but haven't "tested" them long enough in this configuration.
Generally what happens is: you take a call on the phone with Airpods, all good. After 4 to 5 minutes they do disconnect (you hear the disconnecting noise). Then they reconnect after a few seconds, then disconnect again... and this behaviour goes on in a loop.
The problem seems to be more severe when using Whatsapp for calls, but happens also on normal phone calls/facetime. Just less frequently.
Likewise, connection is more stable while connected to computers (Mac mini Intel, M1 MacBook Pro) but the problem still happens. It just takes way longer.