Today I had a walk following old forest road I knew about. As it is not used frequently, in some part a lot young trees and bushes grew up so one has to fight with them in some manner. But it is easily visible and passable as obvious path. It requires no special skills, it does not have steep climbs or so. Passable by anyone.
How should I tag this kind of paths to differentiate them form paths that are clear and easy to walk to?
There is “obstacle=vegetation”. No one will notice, but You can tag it
It sounds like informal=yes may be appropriate. If the path is very overgrown and gets very little use, a lifecycle prefix like
abandoned:highway=path could be appropriate.
It was at one time a road so abandoned:highway=track (or whatever it once was). Highway=path, width=0 (no real tread between bushes). And probably informal=yes as apparently it is not being maintained by some entity. Additional tags like surface, visibility as appropriate.
I would not use informal=yes as wiki states:
a feature has not been established on purpose.
sounds like established on purpose. Therefore the lifecycle should be more appropriate.
If only a short part is affected I would take the obstacle=.