Bug: Gizmo Movement controls going invisible suddenly

Just booted Unity, this was looking fine yesterday, and then I booted today and the gizmo arrows and lines weren't showing up.
Video here: https://imgur.com/a/RqAF89c
After pressing F to zoom in on one of the objects in the scene, the gizmo arrows came back fine.
This is on a regular 1080p screen on Unity 2021.2.0b4.3123

 

I had this issue very rarely. I think this is because of the gizmos going out of the scene camera's far plane. Hitting F to frame the object fixes this for me. I guess Unity should always render the gizmos inside the camera's view independent of where the far plane ends.

 

I can reproduce this. I made a bug report. Case 1353387.

 

The scene view camera's near plane has a tendency to drift. I've never figured out what the trigger is, but it's been that way since Unity 4. It probably doesn't happen if you press F a lot in your workflow since that's what fixes it, but if the workflow is mostly to navigate using the mouse, the near plane will start to drift further and further away after a while of level building.

We've noticed more issues where gizmos and handles just disappear or behave poorly due to this in 2020.2, so it might be that a change to the gizmo handling that's more aggressive about culling (or even culls at all, handles didn't use to do that properly in some instances) makes this bug more obvious.