I’ve been involved with Linux for a long time, and Flatpak almost seems too good to be true:
Just install any app on any distro, isolated from the base system and with granular rights management. I’ve just set up my first flatpak-centric system and didn’t notice any issues with it at all, apart from a 1-second waiting time before an app is launched.
What’s your long-term experience?
Notice any annoying bugs or instabilities? Do apps crash a lot? Disappear from Flathub or are unmaintained? Do you often have issues with apps that don’t integrate well with your native system? Are important apps missing?
Screwed up fonts in GTK software, even though the xdg-portal app for KDE is installed. At some point I just gave up. I see no reason to install any Flatpak if the software in question is already in the distro’s repository and current enough anyway. Maybe except OBS, because the Flatpak version comes with Youtube integration which, to my understanding, needs to remain closed source and won’t make it into a FOSS repository.
I take it you’re on Wayland? The fonts issue is a bug that’s being fixed IIRC in KDE’s portal, but as a workaround for now you can install the GTK desktop portal, which should make the fonts render correctly.
(That is, if you end up needing to use other Flatpaks that have an OBS-like situation)