Siri gets worse with each release. You are not alone. As of IOS15, I cannot request a specific song in CarPlay without first opening the music app. I assume this is due to the addition of alternative providers. however I don't see any options from a user perspective to set Apple Music as my default player. IOS16 has not corrected this issue.

CarPlay notoriously opens random podcasts in Overcast when I request certain songs "From my library."

Siri is a failure, and now I noticed last night my ecosystem is not syncing my DND config. So while I slept in "Sleep mode" on my watch and phone, my iMac dinged and blinged all night. More energy is spent on scanning my photos for unacceptable political commentary meme content Apple prevents me from sharing in messages unless I lighten or darken them adjusting the checksum.