I’d advise against using flatpaks if you also have the software available in the debian repositories. Always use the package manager instead, when possible.
Please let me disagree on this. Debian + Flatpaks is actually an awesome combo. Rock solid and super stable base, up to date user facing apps.
Debian’s life cycle is awesome for core system stuff, it ensures that once your system runs perfectly, it’ll continue to run perfectly for several years without intervention despite always being up to date.
But for user facing apps, it’s actually really frustrating when you know there is a bug fix or a feature you need that’s been implemented and made available months ago but you’re stuck on a 2-year-old version.