Magma Cube Spawn Rate

Magma cubes are supposed to spawn more in Basalt Deltas, but I don't know about the Nether Wastes.

Perhaps the Cubes just kept wandering to the Wastes. 

It literally says in the 20w15a changelog that magma cubes spawn "very frequently" in basalt deltas, so that's not a bug.

Though I haven't been able to reproduce for Nether wastes. They seem to spawn as much as before the Nether update.

I did a little more testing on my world and found that the Cubes kept entering the Wastes from the Basalt deltas. 

I'm very sorry for the inconvenience.