Surface-level Abandoned Mineshafts generate outside Mesa and its Variants

Surface-level Abandoned Mineshafts appear to be generating in several kinds of biomes. I'm not certain, but I think that they are only meant to spawn in Mesa and its variants. Sorry if it's intentional or if this is a duplicate!

What I expected to happen was...:
I did not expect to find Surface-level Abandoned Mineshafts outside the Mesa biome and its variants.

What actually happened was...
I found Surface-level Abandoned Mineshafts outside the Mesa biome and its variants.

Steps to Reproduce:
1. Create a new world. (My Seed: -1921616599526269545)
2. Roam around the world.
3. Find Surface-level Abandoned Mineshafts outside the Mesa biome and its variants. (at "58 83 1094" and "-141 71 1500", for example.)