I don't think there is really much. Most of the bugs you will see stem from software having a different codepath for each. For example I know that drag and drop

I don't think there is really much. Most of the bugs you will see stem from software having a different codepath for each. For example I know that drag and drop is a little buggy on Firefox under Wayland not because of the protocol, just a state management bug that they are trying to track down. (however Firefox still uses XWayland by default so it isn't really relevant anyways). But I suspect we are roughly around the point where the X codepaths, while more battle hardened, are probably starting to rot so the current state you are probably getting the sameish number of bugs under each (AKA applications are differently broken under both). If you are seeing a bug I guess just try the other one out and see if it reproduces, but I can't think of the last time I did that. The only thing that is a common issue is screen capturing not working. If you have PipeWire setup it will work for most applications but it is still quite new. So if something related to screen content grabbing is not working it could be a Wayland triggered bug.