For me it’s the removal and change of UI elements. There is still no built in way to move the task bar to the top or side of the screen and to get a useful right click menu back I have to go into the registry and change a value. There is also the whole thing where you are forced to use a Microsoft account with no option to use a local account instead.
Likely referring to the lemmy.ml instance. We tend to have a reputation of being tankie.