The Bug
According to the Minecraft Wiki, Nether Fortresses are not supposed to generate in the Warped Forest biome and I don't see Nether Fortresses in Crimson Forests. I've been seeing Nether Fortresses spawn in Warped Forests when 20w16a came out, previously they didn't.

How To Reproduce
1) Type the seed on the uploaded picture and teleport to the coordinates on the screen
2) Press F3 on a Windows PC to see the biome you're in
3) Press F3 + G to show chunk borders
-> The Nether Fortress spawned in the Warped Forest Biome, which was an unintentional change