Pretty much all RCS goes through Google servers. They control all the implementations, even in the cases where a carrier has implemented it themselves they likely use Google Jibe system.
If your speaking to someone over RCS you should expect Google to be involved. Even with apple implementing it on iPhone. iPhones are likely to default to iMessage between each other, so the other user is likely an android so messages are getting routed through Google. It’s likely apples decision was based on pressure from Google and the billions of dollars they give apple every year.
Google has repeatedly made attempts to make a messaging app that have failed. RCS is their chosen method to get access to app messaging metadata and it looks to be working. They are displacing text messaging and making it look like nothings changed.