I have same issue,
And in Exactly the same modes,
QHD, HDR10+, Steady Mode, 60fps, HVEC.
I have reported it,
I'm not sure if it's a issue with the Files being saved by camera not saving correct HDR Metabdata, or an issues with HDR10+ Playback.
The over Saturation occurs when played back in Gallery, Video Player, VLC and other Apps that support HDR.
If I open it in Adobe Rush the Colours are fine, But I guess that does not support HDR10+ OR is using its down software decoding or LUT to correct the colour.
I assume its a software issue and it's capturable in a screenshot, which i doubt it woild do if it was a hardware decoder issue.
HDR / HDR10+ content from other video content apps seems to work fine, aka Netflix, Prime Video & YouTube.
The attached screenshot shows the oversaturation of the Red Channel ehen using Video Player and the other is screenshot of Adobe Rush showing the colours as they should be.

