Popups were always fine, I just don’t want TB all time around on my Taskbar that’s why I use Birdtray. I actually did try all variants out but out of curiosity I just did again and you are right X11 directly just works fine too. So it’s just Birdtray having trouble with Wayland which actually is not very surprising since the last update it got is 4 years ago…
Actually this following setup should fix it too and is the better solution:
(thanks to @boredsquirrel for pointing it out)
I am just waiting for the day when Thunderbird notification badges on KDE will be clickable. Although the native notification badge has this feature, they are ugly, and upon clicking them, Birdtray can no longer minimize the opened window of Thunderbird; you have to minimize it manually.
Oh you guys are right! You actually can’t open the message by clicking the notification in KDE. I wasn’t really aware of it since I just tend to read the Notification and come back later to it - hate to interrupt my workflow. Well as far as I read it’s not KDE but TB itself that needs to implement this but since they got more active I hope this will happen soon!