Mangrove swamps generate the Plains variant villagers

I bred some Villagers in my Survival world in an Mangrove swamp attempting to get an Swamp Villager and got confused on seeing an Plains variant.

 

Expected behaviour:

The Villager generated in a Mangrove swamp uses the Swamp variant texture.

Observed behaviour:

The Villager generated in a Mangrove swamp uses the Plains variant texture.