That’s not entirely surprising, for a couple of reasons. One is that there is not much use of that tag yet. Another is that if a style does decide to process them, what does it process them as? When I looked at usage, there was often some other landuse also used. I ended up with this, but that works only because that map style already has a concept of “different tree-covered areas within a larger forestry area” which most other OSM-based maps don’t handle.

(and apologies for continuing the off-topic - happy to continue the discussion elsewhere)