Siri integration will be significantly pulled back for third party apps starting with watchOS 8, macOS Monterey, iPadOS 15 and iOS 15.
Number and types of commands will be reduced in these platforms, as mentioned in the latest developer support page update. SiriKit commands and intents, specifically will no longer be supported in public releases moving forward. Apple listed 22 SiriKit commands on its website, one of which includes not being able to book a ride on apps such as Uber.

Siri will also have reduced capability on 3rd party to-do apps, including Todoist and Things 3, among others. They will not be able to amend a note, delete a task or create new lists via Siri.
In the same vein, bill payments on these apps will be limited. Users can no longer transfer money between two accounts, search a bill or make a payment. CarPlay intents will also be reduced by removing the ability to adjust defroster, seat and climate settings.