Thanks for reaching out on the Community, and sorry for the late response!
Thank you for your feedback. This is currently expected behaviour for the Spotify app when used with CarPlay, and an idea has been submitted in the past to suggest removing this limit (check here), however it didn't gather enough votes.
However, you can create a new idea in the Ideas Exchange here and get others to vote for it. If it garners enough votes, then Spotify might consider implementing it!