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™, when did it all go so wrong? Is anyone else here having similar issues, or am I doing something wrong?
For me, the outdated packages in stable have actually gotten better over time, as DEs get closer to a place where I don’t need any major updates to enjoy using them, Flatpaks become more readily available, and on a subjective level, I get less and less invested in current Linux news. Before Debian became my “forever distro”, I’d hopped to it a few times, and often found myself wishing for a newer piece of software that wasn’t in backports or flathub, or simply being bored with how stable it is, but that’s been happening less and less. And I feel like Debian 12 in particular left me with software that I wouldn’t mind being stuck with for two years.
I’ve gotten warnings to upgrade my browser with Debian’s Firefox ESR, but they never affected a website’s usability in a way that a newer version would fix, and they do provide security updates and new ESR series when they come out; even if you must have the newest Firefox, you can use the Flatpak.
Additionally, I’m currently on testing in order to get better support for my GPU, and each time I’ve tried to use it, it’s worked for me for a longer time than the last as I get better at resolving or avoiding broken packages. If you do experience issues like the one you described, and can replicate them, and no one else has already reported them, you should report them to Debian’s bug tracker. The whole point of Testing is to find and squash all the critical bugs before the next stable releases.