For instance, to right-click method on touchpads without a physical
button you need to perform a two-finger click (just tap anywhere with
two fingers). Clicking in the bottom right area of the touchpad no
longer works.

If you don’t like this behaviour — and there’s a fair chance you might
not — you can use the Tweaks app (see step #5) to change the setting.

Source: OMG Ubuntu (see link for how to fix it)