In the documents there is currently no defined consensus yet. Another option for tagging them would be kick scooter rental but as you can see from the page it warns you as such: https://wiki.openstreetmap.org/wiki/Tag:amenity%3Dkick-scooter_rental 

I think it would be logical to add access, capacity, operator and operator:type but neither of those two schemes above make sense as they specify bicycles which escooters are not.

Voi does happen to be the operator locally but it is a different situation to London where they also operate ebikes whereas in Cheltenham they do not.