You can downgrade packages on a case-by-case, I have done that with network-manager and a few others. But it is manual action and would be infinitely complex for a whole Debian rootfs. So as already mentioned: restore from backups.
I use Btrfs for rootfs and that allows unattended backing up to external devices, but more important also local on same filesystem (snapshots, conveniently done by snapper). So before the edit of sources.list* , I manually do a snapshot with description "bookworm".
In case too much trouble/issues, I set that snapshot back as default, also copy back correct files to bootfs, then reboot and bookworm is back.
Statistics: Posted by redvli — Wed Feb 18, 2026 9:57 am