In crimson forests, the number of piglin brutes that spawn alongside bastions appears to be roughly 1 per every chest in the structure. In soul sand valleys, however, the brutes seem to spawn roughly three times as often. For example, see the attached image of a treasure room in a bridge bastion where 5 piglin brutes have spawned. There were also 3 brutes near the other chest in the structure. Probably related to the new spawning logic for certain biomes.

To reproduce:

-Generate a world with the seed -4716142290296112849

-Teleport to -318, 69, -1 to see a bridge bastion in a crimson forest

-Teleport to -735, 64, -1104 in the nether to compare the same structure in a soul sand valley