I have just spotted that the Weather Underground map WunderMap® | Interactive Weather Map and Radar | Weather Underground is based on OSM, but doesn’t have any attribution showing.
On checking further it appears they are actually using OSM via Mapbox.
The topic of Mapbox not showing our attribution has been mentioned before: WunderMap® | Interactive Weather Map and Radar | Weather Underground & also Lacking proper attribution - OpenStreetMap Wiki
As mentioned in both of those places, chasing Mapbox is well & truly out of the league of ordinary mappers, & is something that should be sorted by the Board.
Has the Board spoken to them?