On the off chance that anyone else out there is running a minimalist Linux system out there for their own idiosyncracies' sake: console scrollback was removed in kernel 5.9 as a consequence of CVE-2020-14390. Use screen or tmux.
By adding "shell -" to /etc/screenrc and "usermod --shell /usr/bin/screen [your username]" you can log directly into a screen-wrapped bash and have scrollback by default again. Separate logins will connect you to the same screen session, which has some implications, but it's interesting. Set "vbell off" and pick some big number for scrollback while you're in screenrc, and make sure /bin/sh points to your preferred shell, which probably isn't dash.
Note that (aaaargh) if you happen to want to pretty up your console some this breaks setfont.
Oh, good - you can solve this in /etc/default/console-setup.
All this nonsense is really only necessary, for certain values of necessary, because unixes were born before single-user machines were economically plausible. I spend a lot of time wondering what a unix that was only accountable to one person would look like, how it would be structurally different. And I think the answer is probably "enough that calling it a unix would be wrong or pointless or both."
