Levels effect not affecting layers underneath when applied to an adjustment layer

The Levels > (RGB) White Input Level effect in adjustment layers might not affect the layers underneath because adjustment layers apply their effects only to the layers above them in the layer stack. You may need to explore alternative techniques for creating a white flash transition. One approach is to modify the blend mode of a solid white layer, setting it to "Screen" or "Add" to interact with the layers below. Another option is to animate the opacity of a white solid layer using keyframes, transitioning from transparent to fully white. You can also use clipping masks to restrict the effect of an adjustment layer to the layers below

The Levels effect with RGB White Input Level on an adjustment layer might not be affecting the layers underneath as expected. This could be due to various factors, including layer order, blending modes, and the specific parameters of the Levels effect.Instead of solely relying on the Levels effect, try adjusting the opacity or blend mode of the adjustment layer itself. Set the blend mode of the adjustment layer to "Screen" or "Add" to create a white flash effect. You can also keyframe the opacity to control the intensity and timing of the flash.You mentioned trying nesting the clips but without success. When using it a nested sequence, make sure the adjustment layer is placed within the nested sequence and not above it in the main timeline. This way, the adjustment layer will affect the clips within the nested sequence.

try Lumetri Exposure or other properties