I think @Boogieberlin does have a point in that there should be an additional page as part of the migration to advise what functionality will be lost as a result.
This does not need to be shown to new customers as they would never have had the beta.
So an “are you sure you want to migrate now?” Question would have been good. Though this does not mean the features will all be back in place before the migrations are forced at least then it a more informed decision.