well thats unfortunate. Personally I’d rather click away one message per year while knowing I donate 40 euros every quarter than having the project die or degrade in the long run.
I think if you complain, you should contribute(either through effort or donation) to make such pop ups unnesseccary.
KDE Plasma albeit a bit bloated in default state is freaking amazing and getting better with every update.
Enjoy whatever DE you Like and complain as you like but just complaining is not going to fix Problems