Unable to answer "Who is allowed to use this playground?" for https://osm.org/node/1978129330 via StreetComplete 55.0:

I am not sure. I have found some signs.

Attached photo(s):
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https://westnordost.de/p/184841.jpg
https://westnordost.de/p/184842.jpg
https://westnordost.de/p/184843.jpg
https://westnordost.de/p/184844.jpg