[3A2D50]

You're right! It looks like the Sony UBP-X700 doesn't automatically detect the HDR type and was set to Dolby Vision. I turned it off and the TV now displays the same HDR logo it shows when connecting to the PC. The AVR says...

  Resolution: 4K24

  HDR: HDR10

  Color Space: YCbCr 4:4:4/BT.2020

  Pixel Depth: 12bits

  FRL Rate: ---

...color are now more aligned with the PC. The Blu-ray video seems to be showing more detail in the explosion. I thought this extra detail was because of more color being shown, but I now think this might have something to do with Youtube's HDR video being more compressed.