This question is pretty much identical to this post, but I just made this account and cannot seem to comment on other posts yet, so I had to make a new one.
In short, I've been trying to do very simple boolean subtractions, and it looks fine in the Blender viewport, but when exporting I end up with a mesh with distorted faces.
For example, the following Arch was made with a cube primitive, cylinder primitive, and the Boolean Difference modifier applied to the cube with the cylinder selected as subtracting object:
However, when I export in either the .obj or .fbx file formats, I get the following in the Windows 3D Viewer:
For the record, I am making sure to apply the modifier, and I deleted the leftover cylinder after applying the boolean modifier.
I initially experienced this on Blender 2.93, so I downloaded the latest version to see if the issue was fixed by an update. I am now on Blender 3.0.0 and I'm still experiencing the issue. Currently on a Windows 10 Enterprise 64-bit machine. Any help/guidance would be appreciated, and please let me know if there's any other information I can provide.