Lets put it this way to simplify this:
You have devices A B C D trying to connect to devices 1 2 3 4 and 5
Device A has issues with 1 2 3 4 and 5 (poor connection, drop outs, stuttering etc.)
Device B has no issues with 1 2 3 4 and 5
Device C has no issues with 1 2 3 4 and 5
Device D has no issues with 1 2 3 4 and 5
Which device you say is the most likely to have an issue? I am saying A and you are saying 1 2 3 4 and 5.
I this case A is the iPhone 11 and 1 2 3 4 and 5 are Apple EarPods, Bose Headsets, Bluetooth speakers, Apple Laptops and different car manufacture head units. This is what I have personally tested with three different iPhone 11 phones.
There is probably some issues on all the devices out there, but I am pretty sure that iPhone 11 has the major issue here as it is the only device in the picture that seems to have issues connecting to everything. The weird part is that it is not every iPhone 11, so it might be some U1 chip tolerance deviances that causes to HW to malfunction. Root cause is still a mystery, even to Apple engineering according to the senior support guy I have talked with.