I just migrated to OmniFocus 2.22 for iOS and 2.12 for Mac via the Test Flight process. My database has been upgraded. The email on this says the release:
adds limited compatibility with test builds of OmniFocus 3, available later in 2018. These versions of OmniFocus can calculate the next repeat for the more complicated repeat rules coming in v3, but those rules cannot be edited.
I can’t actually see any change in the UI, which is probably what the email is conveying (it’s an under the hood thing), but I thought I’d ask here, in case I’m missing something to test.