The distro I'm on getting worse would be one. Linux Mint has been pretty stable and enjoyable though. I admit, setting up a new distro can be fun, but it comes with many annoyances too.
I have been tempted to try KDE and Wayland though. The last time that I installed a new DE, I had all kinds of little reminders of the previous DE that would pop up. (E.g. file selector dialogue boxes.) Finding all the little config options I needed to change to make the switch completely was tricky. At this point, I'm tempted to day that it's better just to install a distro with the DE that you want, but maybe I should try it again.