suspicious tag combination tracktype=grade2 and surface=ground

[dieterdreist]

it seems for surface=ground, German flat land ground is assumed. In the mountains, nearly all tracks and paths are "ground", and there is nothing suspicious in the combination with tracktype=grade2, at least this is what I find everywhere in Valle D'Aosta.

There are 106000 of these in the db:
​https://taginfo.openstreetmap.org/tags/surface=ground#combinations

grade3 10,6%
grade4 9,6%
grade5 6,0%
grade2 3,9%
grade1 0,6%