from https://askubuntu.com/questions/1235067/touchpad-stopped-working-20-04
$ sudo vi /etc/modprobe.d/psmouse.conf
options psmouse synaptics_intertouch=1
$ sudo modprobe -r psmouse && sudo modprobe psmouse
from: https://itsfoss.com/fix-right-click-touchpad-ubuntu/
"Mouse click emulation" to "area" in gnome-tweaks