Firefox on Debian stable is so old that websites yell at you to upgrade to a newer browser. And last time I tried installing Debian testing (or was it debian unstable?), the installer shat itself trying to make the bootloader. After I got it to boot, apt refused to work because of a missing symlink to busybox. Why on earth do they even need busybox if the base install already comes with full gnu coreutils? I remember Debian as the distro that Just Wroks(TM), when did it all go so wrong? Is anyone else here having similar issues, or am I doing something wrong?
TL;DR
You want Debian stable with either back ports or containers. On desktop flatpak is your friend. Also do not add extra repos.
Honestly there is little reason to not use flatpak for web browsers. If you want packages from Fedora or other distros you can use Distrobox with podman as the back end.