I can confirm this, but this seems like a limitation than a bug. Issue is that you are projecting vertices from behind camera. Also do you have reason adding @Sergey Sharybin (sergey) as subscriber?

You can cut your mesh like this to produce sensible UV

I was thinking, that maybe we can clip vertices behind camera like in following patch, but I don't think it would be possible to maintain correct geometry.

diff --git a/source/blender/blenlib/intern/uvproject.c b/source/blender/blenlib/intern/uvproject.c
index 00fef29587c..3e655e529da 100644
--- a/source/blender/blenlib/intern/uvproject.c
+++ b/source/blender/blenlib/intern/uvproject.c
@@ -68,8 +68,8 @@ void BLI_uvproject_from_camera(float target[2], float source[3], ProjCameraInfo
     }
   }
   else {
-    if (pv4[2] == 0.0f) {
-      pv4[2] = 0.00001f; /* don't allow div by 0 */
+    if (pv4[2] >= 0.0f) {
+      pv4[2] = -0.00001f; /* Don't allow div by 0 and clip everything behind camera. */
     }

     if (uci->do_persp == false) {

I can confirm this, but this seems like a limitation than a bug. Issue is that you are projecting vertices from behind camera. Also do you have reason adding @Sergey Sharybin (sergey) as subscriber?

The reason Sean CCed me is because I've asked so. To me it is not so obvious why some of the points behind camera are projecting wrong. It is also not something what is intuitive from the projection happening in the motion solver.

You can cut your mesh like this to produce sensible UV

This wouldn't work for VFX usages, where camera is not still and might move/rotate, and projection happens from image sequence.

I was thinking, that maybe we can clip vertices behind camera like in following patch, but I don't think it would be possible to maintain correct geometry.

For the simple case this works, but if you subdivide the mesh few times in edit mode and project form view again then the UVs are broken again.

Interesting puzzle eh :)

If you need clearer example, I have moved camera a bit closer to corner of one plane so you can see better the situation. Edges coming from behind camera looks like they are diverging the closer they get to camera, but in reality they are converging to one single vertex. That's why I think it is impossible to make good UV, unless one vertex can be somehow represented by more "virtual" vertices in UV editor.

@Campbell Barton (campbellbarton) it is always a good communication to explain why something what was considered a bug all of a sudden became a known limitation. This solves confusion of reporter and everyone else who is interested in this topic. Additionally, giving more details will help future-you and everyone from the community who would want to fully solve the limitation.

As for the suggested workaround, I do not see how it helps. The "offending" vertex will still be projected to the "wrong" position. But on top of that you'll have even more vertices which are not properly mapped: