Thanks for the answer!

I'm not saying Zood isn't safe to use, but security isn't binary, and a centralized service is always a more lucrative target than a self-hosted one just because there is more data there. And it's also not just a technical question - what stops you from being acquired by $MEGACORP, pushing an update which removes the E2E and start mining the data? That (the acquisition, not the E2E removal) actually happened to me before[1] with a location tracking app.

[1]: https://www.pcmag.com/news/facebook-acquires-fitness-trackin...