In general, Frankfurt suffers from many wildly placed separately sidewalks, mostly due to some users (or most likely, one specific user if you look back into the history of all such sidewalks) who don't know that unmarked crossings (i.e. virtual paths) also have to be mapped, alongside other issues (like not fixing road crossings).

I've added some crossings but overall, the sidewalks mapping here is pretty bad and many users have complained about it.