Sound Bug with Fairphone 3 preinstalled /e/

I am experiencing an quite anoiying bug with my fairphone 3 Android 10 (Build: e_FP3-userdebug 10 QQ3A.200805.001 eng.root.20201214.232210 dev-keys,stable-release)
Sometimes when I remove my headphones the internal speakers will stop working. Instead, if they should play a sound, a short bass noise is repeatedly created until the soundsoucre is turned off. Only by repeatedly rebooting the phone this bug will dissappear, only to randomly occur one again when I switch from headphones or bluetooth back to the internal speakers.
Did anyone else had this bug and can give me adive how to deal with it?
Thanks for your help!