QUESTION/Potential Bug HDR Max luma not respected in certain videos?

[streetpea]

I noticed in certain videos (using the Vulkan renderer of libplacebo, haven't tested with other renderers), settings the colorspaces hdr.max_luma cuts the max CLL reported by the Steam Deck hdr analysis or the reshade hdr analysis tool (https://github.com/EndlesslyFlowering/ReShade_HDR_shaders) to max out and around the max_luma value when playing the video but with other videos it only does this to a specific cutoff point, say 520 nits and then jumps to the max of the output (say 1,000 nits or 10,000 nits) instead of staying around/under the max_luma value. I'm not sure if this is a bug or expected behavior in certain instances?

Additional info: I printed out the max_luma set by the target frame to make sure it was being set to whatever the value was and it was reporting a max_luma of say 600 nits while the output was 1400 nits or higher in those instances. Here is the code that sets the max_luma to the target peak value in the settings (https://github.com/streetpea/chiaki-ng/blob/e61047fc007909c6a694688c7bc3096089f263d6/gui/src/qmlmainwindow.cpp#L829).