Ciao Remi
Here you've added https://www.openstreetmap.org/way/1377989105 as a *circular* stream.
This makes it show up on https://waterwaymap.org/loops/#map=16.37/48.342413/6.639323 as possibly wrong.
Could this be an intermittent pond and not a stream?
Happy mapping and greetings from Switzerland,
habi