You can reproduce this by installing tmux and running it locally (or running it remotely after ssh'ing into a system with tmux), and then typing return a large number of times until you get to the bottom of the screen. Tmux will try to set up a scroll region so that you don't mess up the tmux status bar when you scroll past the bottom of the screen. But this doesn't work with GNURoot's terminal emulator, which makes using tmux basically unusable.
The terminal emulator in TermUX does get scroll regions correct (tmux works correctly with TermUX), and its source code is available in Github, so this should be something which is fixable by looking and boorrowing its code.
You can reproduce this by installing tmux and running it locally (or running it remotely after ssh'ing into a system with tmux), and then typing return a large number of times until you get to the bottom of the screen. Tmux will try to set up a scroll region so that you don't mess up the tmux status bar when you scroll past the bottom of the screen. But this doesn't work with GNURoot's terminal emulator, which makes using tmux basically unusable.
The terminal emulator in TermUX does get scroll regions correct (tmux works correctly with TermUX), and its source code is available in Github, so this should be something which is fixable by looking and boorrowing its code.