Quest 2 does not update Camera.targetTexture properly

Unity forum post here: https://forum.unity.com/threads/camera-targettexture-lags-behind-main-camera.1242781/

I was investigating an issue with Camera.targetTexture not updating properly. Then, I realized it works just fine in Unity's Game screen, but not on the Quest 2.

I have a main camera controlled by a TrackedPoseDriver. And a secondary camera that follows the position and rotation of the main camera, but with an offset in position.

The secondary camera has a targetTexture, and I render the targetTexture on a Quad.
For some reason, the targetTexture makes it look like the secondary camera is always "lagging behind" the main camera.

Again, this "lagging behind" does not happen on the Game screen, only on the Quest 2's screen.

When I don't move the main camera, the image is exactly what I expect to see.
When I do move the main camera, the image is updated a few frames behind, effectively lagging or having a delayed response.

How can I fix this so that Camera.targetTexture updates as often as it should?