Carplay is playing at one side only
I noticed some people complaining of carplay playing sound only on right speaker only in the car .. and your answer was to clean the socket and contact apple support
i had the same issue but i managed to fix it through
setting /accessability/ airpods /audio accessibility settings/ then under balance take it to the middle .
this totally fixed the problem and tried it on many times so i hope this help others having the same issue ..
iPhone 11 Pro Max, iOS 15