I don't use iCloud Relay but it seems Apple's ASN would be 'reputable'.
https://support.apple.com/en-us/102602
"As mentioned above, Cloudflare functions as a second relay in the iCloud Private Relay system. We’re well suited to the task — Cloudflare operates one of the largest, fastest networks in the world. Our infrastructure makes sure traffic reaches every network in the world quickly and reliably, no matter where in the world a user is connecting from."
"Bad guys" using Private Relay is one reason these IPs get blocked: one abuser can cause an entire block of people to get flagged as a single malicious user; and a big enough group of users can also look like a single malicious user to many blocklisting strategies, because they all share the same IP.