I read the discussion at
https://www.openstreetmap.org/changeset/42078447

Yesterday at late morning it still seemed disused. I didn't find a button or similar and guess the water should just flow if working properly. Or did I miss anything? Could have asked at the pharmacy, but thought about that too late.

In principle it looks similar to this one (water leaves from the top downwards):
https://de.m.wikipedia.org/wiki/Datei:Font_Wallace_Grd_Pont_Neuf.jpg

All in all "disused" seems to be correct, also rather than "seasonal", so I fixed the conflicting tagging: https://www.openstreetmap.org/changeset/135163790