Snap and Flatpak take up way more room than I think make them worth it. It is like each app takes up nearly a whole embedded OS’s worth of disk space. Certainly try to use the “native” RPM packages for apps when you can using snap or flatpak only for apps you cannot find as RPMs. And then stick with one or the other, not both snap and flatpak.
One could also probably move /var/lib/flatpak to /home and symlink to it there. But only if the flatpak service is not running at the time.