I was searching for Nether Fortresses to see how the new Nether would be like on the world I'm currently playing on and noticed that when using /locate, it suggested a Fortress that's ~600 blocks away, even though there's one only ~150 blocks away.

This seems to happen not just with Nether Fortresses as after further testing, structures in the Overworld also seem to be affected by this. I discovered this issue persisting with a Village and Pyramid nearby.

Seed: -648154640804575350

Fortress Test:

Location in Nether: -50, 69, 63

Nearest Fortress: -177, ~, -42

Result from Command: -608, ~, -224

Side note: The moment I cross over to chunks z=-1, the locate command gives the correct answer

Pyramid Test:

Location in Overworld: -2, 69, 575

Nearest Pyramid: 176, ~, 608

Result from Command: -1024, ~, 208

Side note: The moment I cross over to chunks x=0, the locate command gives the correct answer

Village Test:

Location in Overworld: -274, 65, 511

Nearest Village: -480, ~, 272

Result from Command: -1024, ~, 176

Side note: The moment I cross over to chunks z=32, the locate command gives the correct answer

As seen in the side notes, I think the issue could be related to chunks.