Mixing of OAS 3.1 API with OAS 3.0 DOMAIN - is it possible?

Hi,

It is great to hear that OAS 3.1 is now supported. I tried right away to "upgrade" one of our APIs to 3.1

Since we are using Domains - this does not seem to work unless all Domains referenced are also upgraded (I have not tried to upgrade them yet).

Would that be a correct assumption? Or could something else be wrong?