Steps to reproduce:

1. Create a new 3D URP project
2. Create a Rendering -> Render Texture in the Project
3. Assign the Render Texture to the Main Camera's Output Texture field
4. Observe the aspect ratio of the Camera's frustum in the Scene view (is square)
5. Change the Render Texture's size to 1920x1080
6. Observe the aspect ratio of the Camera's frustum in the Scene view

Actual results: We need to disable and re-enable the camera GameObject to update the gizmo to the correct aspect ratio

Expected results: Updated to a rectangle of aspect ratio 16:9 automatically the next time the camera is selected

Reproducible with versions: 2023.1.0a10, 6000.0.73f1, 6000.3.13f1, 6000.4.3f1, 6000.5.0b5, 6000.6.0a3

Tested on (OS): Windows 11 Pro

Workaround: Disable then re-enable the Main Camera or reassign the Render Texture reference