The Bug - Affects 20w16a
The Nether Fortress spawns are way less common as before and it was not mentioned in the change log. When the Bastion Remnants were added into the nether, the spawn rates of the Nether Fortress has changed for no reason.
How to Reproduce
1) load 20w15a and 20w16a
2) create a world in both versions with cheats using the seed 35267400
3) type the command /execute in the_nether run tp 0 100 0
4) type the command /locate Fortress
-> You can see that the fortress spawns changed without mention
Note: this report may be a feature request or an unintended bug.