Recently, Apple releases new software system IOS 15.0 Carplay, but there is a software bug at carplay function.
If carplay runs on phone with IOS15.0 system, as long as carplay plays music, no matter from which music APPs even apple music, the carplay will happen carplay logout, failed disconnect, connection, or unable to play music.
This is a IOS system bug on carplay, and there are 2 solutions.
1, Short term solution
At phone settings — General — Transfer or restore iPhone — Restore — restore all settings.
Pay attention what you need to do is restore all the settings, without affecting the data and software
2, Long term solution
Wait new IOS system from Apple