"It is actually quite normal that Blender’s native render viewport preview cannot display VFB effects such as OCIO and exposure. This way, the native compositor and the VFB effects do not interfere with each other.
However, I have an idea to strike a balance: we could add a toggle button to decide whether to synchronize the VFB effects. If synchronized, the VFB effects would be shown in Blender’s native render preview, and the compositor would be automatically disabled by default. If not synchronized, the native render viewport preview would not show VFB effects, only the compositor’s results.
This way, there would be no conflict between the VFB and the compositor. As a Blender user, I personally prefer using the native viewport render preview over the VFB, because using the VFB means an extra window, and you still have to rotate the 3D view in the native viewport, which makes the workflow rather cumbersome."