I don't like the donation popup because i already have a monthly donation running. They should provide donors with a code to turn this stuff off :(
To turn off the popup, head to System Settings -> Notifications, search for "Donation Request" and turn it off.
I should have looked for it myself but every time it happened I was busy doing something else and then I forgot (yay ADHD).
And thanks to you for making KDE. I really don't like this time where computers are becoming more locked-in and opinionated (e.g. I can't configure it the way I want). KDE is a breath of fresh air. I have extensively reconfigured it and I haven't even needed to use a single plugin. So I've donated for years now because I really appreciate the work.