Edit Moderator:
Original text deleted as it was off-topic.
Maybe I’m too green, but also cannot figure out how to change a detail in OSM.
Are you willing to give a helping hand on that one?
@Guenniguenzelsen you know that location in person?
Do you mean the encircled traffic sign?
In this case it can be solved with a turn restriction
- select the crossing
- than select the “from street” and the “to street”
In this case there is an exception for bicycles:
To add this exception click on the turn restriction.
… and add the exception for bicycle.
As a last step, you should mark the note as “resolved”
I did not make the actual change, so you can practice yourself 
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