Oh yeah, sorry!

I investigated it with an android phone and found out, that the cookie banner component is the one which causes the error

Works fine for me also looking at the code it doesn't do anything on signup form or a global JS files. Remove birthdate only initiated on profile edit form. No where else is initiated.

I found another bug:

some android users are reporting, that they can't open the birthday field on signup form - when I disable the component, it works

I found a bug - ossn 7.5

If you clicked on the birthday field on signup and accidentally closed it, you can not open it up again, you've to reload the site

Thanks!!!

I will test it :)