If you are using d3d11va then SVP doesn't work properly because it doesn't have full access to all frames.
Never had such an issue with RIFE + SVP + MPV
Also hwdec has very little to do with colours which is why you see no differences. But it might have some impact on banding depending on what card you are using.
Pictures look exaggerated, captured with ExpertRAW on my phone. But you can understand what I mean by banding, and the blacks are not perfect blacks, they become very very dark grey, but not perfect black levels.
hwdec=d3d11va
hwdec=d3d11va-copy
As to this:
Anyway if you have GSync monitor with physical module, this issue isnt happen, because renderer now doesnt request backup memory through VRR option!
It's an LG C2 42" which I use as a desktop monitor. It has both GSync and Freesync Premium.
Either way, I am still looking for a solution. Maybe someone else can chime in if they know of a workaround or different rendering method perhaps.