I think the problem with btrfs is that it entered the spotlight way to early. With Wayland there was time to work on a lot of the kinks before everyone started seriously switching.
On btrfs a bunch of people switched blindly and then lost data. This caused many to have a bad impression of btrfs. These days it is significantly better but because there was so much fear there is less attention paid to it and it is less widely used.
I just think people who have issues with Wayland and btrfs are hitting bugs that developers can’t trigger. It’s an unfortunate situation but these people should work closer with developers to get them more info.
The situation sucks because Wayland and btrfs offer so many features but there’s those few people who can’t seem to get them to work reliably.