A few weeks ago, I got the moisture detected in charging port alarm/error message on my Galaxy S21+. The phone hasn't been in contact with any water at all.
After browsing forums, I worked out that the issue is with Android Auto. When I plug the phone into my 2021 Toyota Rav4 before turning on the ignition, the alarm sounds. This then persists and will sound if I try and use a regular phone charger.
Once it's cleared (I can force stop the Android System app to do this), it'll work fine with a regular charger up until it's triggered by plugging it into the car again.
The weird thing is that if I start the car before I plug in the phone, then plug it in, the alarm does not sound and Android Auto works fine. I also have to remove the phone before turning the engine off, or the alarm/error returns again.
The phone otherwise works perfectly, so this has to be some sort of software issue with either Samsung or Android Auto. Both are on the most current version here in the UK. Has anyone else experienced this? Any solutions?