Just yesterday I used Jellyfin2Samsung to install Moonlight on my TV. After the installation, the app shown a popup to donate to the author ("buy me a beer"). And I figured why not? The software turned a tedious process into a one-click solution, letting me do what I wanted to do (stream games to my TV) rather than spending an evening messing with Tizen Studio. Absolutely worth a few dollars.

KDE's Plasma will popup a notification every once in a while asking for donation. When you close it, you won't hear from it again until the next fundraiser. I almost always donate as well.

If a software asks in a non-obtrusive way, ideally after I used it (either for a while or like in case of Jellyfin2Samsung after doing the one thing it's supposed to do), I don't mind at all.

I dislike apps (mostly websites) that keep asking for money, regardless of whether you already donated or not every single time you visit them.