Isn't it more a problem of using something like QGnomePlatform and Adwaita-qt? AFAIK they cause a lot of issues and there are plans about discontinuing them in Fedora.
Since you are running firefox instead of ./firefox, I guess you are using your system-wide firefox anyway. You can just use the built-in profile manager instead.
The current version has some problems with adaptivity, e.g. resizing the app window can cause issues. This led to the creation of new libadwaita widgets. If you want to read the technical details, see https://blogs.gnome.org/alicem/2023/06/15/rethinking-adaptivity/
That's what I love about Rust: many problems that would turn into runtime errors in other languages aren't possible with its type system and the compiler catches them.
Some applications are available as Flatpak only, because it makes no sense to maintain 2-5 different packages of the same program for multiple distros, when you can also maintain 1 package for all distros.
https://jpegxl.info/why-jxl.html