 Hi FenyMufyd. thank you for contributing to OSM.
I do armchair to this area. I found several warnings about multipoygon 
https://www.openstreetmap.org/changeset/133553401

I see a long segment of wood around without a specific area shape only a square in this area nor a specific role in relation. 

but multipolygon represents areas (polygons), typically complex areas with holes inside, or consisting of multiple disjoint areas.

I am curious about this area. would you mind coming to recheck? perhaps this common polygon landuse./natural without relation more appropriate.

thank you