Although not open source, I use Obsidian since its really extensible, works completely local and has open source extensions. I thought about using Logseq too. I’d never trust Microsoft with my personal notes tho.

Some german politicians have also tried time and time again to establish data retention policies because “think of the kids” argument blablabla. But so far they have failed to do that as it was proclaimed unconstitutional by our federal court. Some politicians play with the idea from time to time tho.