I upgraded to IOS 18 earlier this week. When I used Apple Maps on Carplay last night, Siri would only say that it was looking for directions. The destination never came through CarPlay. It should have been an easy one, as I was taking someone to the airport to fly to Atlanta.
You should probably raise this as a bug in the usual way. It won't really get progressed if it's only posted in these Developer Forums, because these forums are where third-party developers chat about issues in their code.
You need to raise each issue you find separately at https://feedbackassistant.apple.com/ You can post the FB numbers here if you want, so that others can link to them.