I used Matomo for a while for a few of my non-monetized sites, and like you, I found it to be just a little too much for small projects. I switched over to Shynet a few years ago - basic, easy to understand, and self-hostable. I noticed it's a lot more accurate than Matomo was, probably because it's on fewer adblock lists. I wouldn't be bothered to see my browser making requests to an instance either since it's pretty respectful of privacy and doesn't collect much.

I fixed a similar cursor issue that started with Plasma 6 in KeepassXC (not the Flatpak version though) by installing extra/breeze5 and extra/plasma5-integration, suggested in this thread. Maybe it will help the Flatpaks too?