Oh, that's bad. But you're right. They seem to be large numbers now. Might be hashes of the names or something, or just plain GUIDs.
I think they were never meant to signify what order they're rendered. They're layer IDs.
This was the behavior in 4.x too. The layer draw order could be IDs: 2, 1, 3, 4.
I actually haven't seen how submesh renderers are handling sorting layers. You're supposed to just type the number?
