I returned my iPhone 11 Pro Max.
Best choice I've ever made.
Even low end budget phones from alternative competitors (which I'm using for now) has much more stable bluetooth.
I switched to apple again for that short time because I was told apple had good support, due to Android's being so fragmented and by many companies.
Well, Apple support was no better. They had no knowledge about the issue, even when pointed to this post. They did nothing to help resolve it besides look up info on their FAQ page, there is no top level support from what I see, just peons reading a FAQ "Have you reset your phone? System Restore" etc etc...... The only solution was to keep getting replacement phones sent out to me until it magically is fixed.....
I am baffled how no tech reviewers caught any issue like this. It almost makes me think they never really use a phone like a real person. As this issue does not seem to be a few isolated cases, as demonstrated by this thread.