Changing the transform handle width to 1 pixel makes the vertical handle disappear when the scene view is an even number of pixels wide. This does not happen with 2 pixels or zero pixels, which is weird.

While we are at it: having a zero-pixel wide setting that shows something is weird.

Might happen on other screen sizes, but my screen resolution is 3440x1440.

How can we reproduce it using the example you attached

1- Change the transform handle width to 1 in the Scene view preferences
2- Resize your scene view so that it has an even number of pixels
3- Observe the vertical (green) handle disappears