I recently got my Moto G4 Plus and it has got a turbo charger too. On charging it using a specific plug/socket, the phone just starts tapping randomly. When charging through another point, it works fine. Why? Is it the current issue?
Moto, as with some other manufacturers do this. It sucks as I've experienced it in the past but the phone is just sucking in power, and while you try to touch it it gets intercepted or there are just random touches. You can't really do anything about it other than let it charge and use it while its not charging.
While there is an accepted answer, it is worth pointing out that this behaviour is only observed by OP in one particular charging point and is fine otherwise
This is probably because that point has grounding or other electrical issues, which is leading to this behaviour also called ghost touches. Googling for that would lead you to similar conclusions. I have often experienced this traveling in Indian trains, where the charging points are apparently not well regulated. Andrew (thanks) has located a proper electrical reasoning for this in comments