There have been no changes to how sharding works, especially not within the last day. Keep in mind there is a difference between sharding (which shouldn’t currently be active on RP realms) and Cross realm zones. In either case, those should only be happening, when it does, between like realms. RP realms should not be connected to non-RP realms.
Note, that doesn’t prevent folks from grouping with folks from non-RP realms and them joining an RP person on their realm when grouped.
If you believe you are being sharded or CRZ’d with non-RP realms please be sure to submit a bug report,