I guess it depends which portion you look at. If you solely look at the time based portion you do indeed still have a function which never decreases but that is true even in the case of reading the raw counter whole on its own anyways. If you look at the whole value, including the hashed portion, it's no longer monotonic.
In the cycle based case looking at the whole value is the same thing as looking at a relative time stamp which has more precision that the system clock. In this way, it's "truly" monotonic across the entire value, not just monotonic on a part and unique in another.
Side topic: It also comes with an even stronger guarantee of always increasing instead of just "not changing direction". Is there a name for that?
In the cycle based case looking at the whole value is the same thing as looking at a relative time stamp which has more precision that the system clock. In this way, it's "truly" monotonic across the entire value, not just monotonic on a part and unique in another.
Side topic: It also comes with an even stronger guarantee of always increasing instead of just "not changing direction". Is there a name for that?