Weird (Renderer?) Visual Glitch

[ReX]

I just encountered a weird visual glitch. Looking at an area at a certain angle shows everything as it ought to be. Lowering the field of view fractionally really messes up the view. Lowering the field of view again resolves the issue. So it's only when the view falls within a narrow angular range. This problem does not seem to happen from every possible viewpoint, but I haven't tried changing position too much.

GZDoom v3.7.2 Legacy; hardware acceleration (not an external video card)

Here is a normal view of the scene:

Normal Rendering

Here is the messed up view of the scene:

Messed-up Rendering

[Rachael]

First and most obvious question is going to be - what is your GPU?

We should also know your operating system and what kind of CPU you have.

[Graf Zahl]

Also important:

What map?
What does the modern build do?

[ReX]

@Rachael: I can’t check right now but will send info as soon as I can.

@Graf: 1. It’s a custom map (WIP), which I can send you if needed
2. I haven’t used the newest build, but I’ll download, try out, and report back

[Graf Zahl]

I'll still need the map to analyze the problem.

[Rachael]

Rex seems to do a lot of hit and run forum visits. He'll be here for a few days and then he'll disappear for a couple months. I'm hoping that he won't forget about this, though.

I'm just letting you know, in hoping to make it less likely you'll close this.

[Graf Zahl]

Still no response.
But seeing that this is the vintage build and ReX having said he's still using old hardware, I am now moving this to the proper subforum.