I thought it would be great to spread awareness about this issue, hence I'm sharing it with you here.
In X11 there is a nice feature called "Turn off touchpad while mouse is plugged in" - it's a lifesaver when you have a laptop with big touchpad; me and lots of people with this issue accidentally hit it all the time while typing.
However in Wayland this setting is missing. After some digging people found out that this is not an issue with the libinput driver itself (used for touchpads on Wayland), as it is supporting this feature for a while now; rather it's an issue with the settings app itself, simply not implementing this feature while using Wayland.
Hope this will get attention from the community, as the recognition from the dev's side is minimal.
Have you filled a bug/feature request for this or found existing one to make sure someone can can address that? The feature seems obvoius fir you, but apparently it's not so important for vast majority of users. For one I never used it and don't feel like doing so.
For now, you can work around it by binding a keyboard shortcut for touchpad toggling.
Check the link I've provided above. It has been reported in December 2019.