Something along those lines is actually highlighted for Private Relay connections:
“All connections that use Private Relay validate that the client is an iPhone, iPad, or Mac and that the customer has a valid iCloud+ subscription. Private Relay enforces several anti-abuse and anti-fraud techniques, such as single-use authentication tokens and rate-limiting. This is designed to ensure only valid Apple devices and accounts in good standing are allowed to use Private Relay.”
“All connections that use Private Relay validate that the client is an iPhone, iPad, or Mac and that the customer has a valid iCloud+ subscription. Private Relay enforces several anti-abuse and anti-fraud techniques, such as single-use authentication tokens and rate-limiting. This is designed to ensure only valid Apple devices and accounts in good standing are allowed to use Private Relay.”
https://developer.apple.com/support/prepare-your-network-for...