Thanks for your reply. I can surely test the mics by taping one of them the next time in the rehearsal space. But that should not be the long term solution.
In this discussion Very low quality audio recordings people say that the problem of the “auto gain filter” is solved, but obviously just in the camera app, not when using recordings apps like “audio recorder”. I’m not sure about contacting the support with it because this problem is or was on a list to improve things with the next update. It would be helpful if someone else would try to record loud music (concert for example) with this app by using the unprocessed mic setting