I think the post is very explicit. First sentence:
reply> Starting later this year, new Sign in with Apple addresses, previously issued on privaterelay.appleid.com, will be issued on private.icloud.com. Existing addresses on privaterelay.appleid.com will continue to work and forward mail to users without interruption.
That's the Sign in with Apple domain, not the Hide My Email domain. HME is remaining at icloud.com instead of moving to private.icloud.com as well. From the linked article:
reply> After further consideration and reviewing community feedback, iCloud+ Hide My Email addresses will remain on icloud.com.
How many sign ups you have with an @icloud.com address?
replyA lot of those are Hide My Email aliases that, by design, you can’t tell apart from real human addresses.