Nether fortresses usually have closed hallways after the well room(each fortress has one well room) that generate with chests and nether wart. In this bug, said hallways are nearly nonexistent. (It does not always happen, but it does so too often to be comfortable) Edit: this bug also exists on older snapshots, but I am not sure what the oldest one is. I have not yet confirmed the bug for 20w21a because I have not looked into it.

For people that deal with these bugs:

Seed: -9222046953685220145

Coordinates: -193, 59, -369