If you are seeing this in a console (not in a GUI Terminal window), then it's "normal". Since kernel version 5.9, support for the scrollback buffer has been removed. See
In a console, you can use less or screen instead.
If it's just a single command which outputs more than a screen and you want to see it all, pipe the output through less :
your_command | less
If it's for interactive use or several commands, start a new screen session (eg. screen -RD), and use that to enter your commands. To view what has scrolled out of the screen, use Ctrl-A Esc. Then you can use PageUp/PageDown. To exit that mode, use Esc.
To exit the screen session while keeping it running, use Ctrl-A D (Disconnect). You can then re-attach to that session with screen -RD (or screen -r your.session.id if you have multiple sessions in the background))
See man screen for all the details. Or inside a screen session, use Ctrl-A ? to view the available commands.