Hey, Frank, I’m only a customer. But I’m in the same process of having to migrate an existing site to a brand new WordPress instance on a different domain. And in the process of doing so, the migration wizard popped this same remark as you wrote. It was an obvious indication that the mapping from the source site to the target site were not equivalent as not only were their domains different. So, I think it’s more an alert than anything, since I clicked past it and the migration happened.
My issue is different (the wrong backup files got transmitted). But as far as something being migrated from one site to another is concerned, once you click through this alert, the transfer should happen as indicated.
Alexis