Beginning with DebianSqueeze, Debian uses Dash as the target of the /bin/sh symlink. Dash lacks many of the features one would expect in an interactive shell, making it faster and more memory efficient than Bash.
From DebianSqueeze to DebianBullseye, it was possible to select bash as the target of the /bin/sh symlink (by running dpkg-reconfigure dash). As of DebianBookworm, this is no longer supported.
No no no no no, do not believe this you will shoot yourself in the foot.
https://wiki.debian.org/Shell