Camera3D preview may show temporary visual glitch when selected

[kitbdev]

Tested versions

• Godot v4.4.beta1
• related Add Camera3D preview in Inspector #90778

System information

Windows 11 (build 22631) - Single-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2070 (NVIDIA; 32.0.15.6614) - Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz (12 threads)

Issue description

When there are multiple cameras and you switch between them, there may be a short visual glitch in the camera preview.
It doesn't really need multiple cameras to happen, but it happens less often.

godot_cam_preview_glitch.mp4

Maybe related: the preview updates late in some cases, see #90778 (comment)

The preview should not show anything until it is ready.

Steps to reproduce

1. Add 2 Camera3Ds to a scene.
2. Repeatedly switch between them while watching the preview.
3. You may see visual glitches.

Minimal reproduction project (MRP)

Not really needed but here:
camera_preview_multiple_2025-01-17_15-18-50.zip

[JekSun97]

I also see this problem in Forward+:

However, in Compatibility mode, another problem occurs: the texture from the camera does not have time to be drawn and displayed instantly:

0118.2.mp4