Andy from the Data Working Group here - I reverted the vandalism last week.
I’ve sent a message to the contact address on that website explaining what happened and I’ve suggested that they might want to consider force-rerendering the problem tiles.
We’ve seen this kind of problem before - for all sorts of good operational reasons organisations sometimes apply updates from OSM sparingly, or don’t update tiles very often, and the best thing to do is to simply let the site operator know that there is a problem.
In this case it’s clear that the data did come from OSM, but we (the DWG) do also see reports where people see data that’s a combination of various different sources, see a reference to “OSM Map Data” at the bottom of the app screen and think everything they see is from OSM when it may not be. A social network app might display search results from their own data, or even from contact information on a user’s phone, on top of an OSM map.
If you wonder where data is coming from please do continue to ask about it though, either somewhere like here or (if you think there’s been a data breach that the DWG needs to be aware of) by emailing email@example.com directly.
I’ve just had an automatic reply back saying “we will read but might not answer this message” and pointing people at their forum https://www.lightningmaps.org/forum . If there’s no change to the background map in the next few days I’d suggest posting there.