Debian strongly recommends against adding repos from other distributions or other versions of Debian: https://wiki.debian.org/DontBreakDebian#Don.27t_make_a_FrankenDebian Doing that can easily break your system. They also recommend against adding repos for specific software packages (e.g. for LibreWolf), but this is generally less problematic.
Personally, on Debian, I try to get packages in this order:
From the official Debian packages
From Flatpak
Pre-built binaries (I put them in my home, not in /usr/bin)
Debian strongly recommends against adding repos from other distributions or other versions of Debian: https://wiki.debian.org/DontBreakDebian#Don.27t_make_a_FrankenDebian Doing that can easily break your system. They also recommend against adding repos for specific software packages (e.g. for LibreWolf), but this is generally less problematic.
Personally, on Debian, I try to get packages in this order: