[quote=@Guardian Angel Haruki]
The new subclass third rule would make sense if the deity a cleric worships has multiple domains. But if it has only one? Then it's like the Warlock Patron issue again.
[/quote]

I think that can be worked around as well. In mythology, deities gain new domains all the time. For example, Apollo being a sun god and Artemis being a moon goddess are actually fairly recent additions. Leaves it open for the cleric to perhaps learn more and interpret their deity in different ways. After all, as shown in the Planescape setting, belief can be surprisingly powerful.

(tbf I do agree with the warlock thing. It is the most difficult to work around, though not impossible. For example, a fiend taking on a more heavenly disguise when offering their pact for the first time... still frustrating though, and I do wish they hadn't ruled it like that xP)