As everybody else has said, Debian is working as intended. To respond to the actual post though, Debian is working exactly as it always has.
If you think Debian used to be good, you must really love it now. It is better than ever.
Unlike in the past, the primary drawback of Debian Stable ( old package versions ) has multiple viable solutions. Other have rightly pointed out things like the Mozilla APT package and Flatpaks. Great solutions.
My favourite solution is to install Arch via Distrobox. You can then get all the stability of Debian everywhere you need it and, anytime you need additional packages or newer packages, you can install them in the Arch distrobox. Firefox is a prime candidate. You are not going to get newer packages or a greater section than via he Arch repos / AUR ( queue Nix rebuttals ).