Nice work
EvilBoris and Digital Foundry on kinda uncovering this. It's disappointing.
That said, I am on record in some of the other threads about this issue having said that I prefer the HDR on despite its "fakeness." Well, I retract that opinion as I had not actually done extensive tweaking and playing around in SDR.
To restate my setup from other threads:
My TV is an LG B7A OLED. I own both PS4 Pro and Xbox One X copies of Red Dead Redemption 2.
Last night I decided to do a bit more of an extended session of play with HDR disabled on my Xbox One X, whereas I had ONLY disabled HDR on the PS4 Pro version before because it is an in-game toggle. If it had not been reported before, I think that the HDR toggle in the PS4 Pro version might not communicate to the LG B7 very well and actually disable HDR, or the TV itself does not accept the HDR disable toggle properly. To expand on that, when I went to try SDR on Xbox One X, I had to disable HDR at the system level as that version of the game lacks an HDR toggle in-game. Doing so actually produced a very, very satisfactory image that seemed to have appropriate contrast and much more vibrant colors. This was NOT my impression when I ran the HDR-off test on PS4 Pro two nights back -- what happens on PS4 Pro is that when I turn it off in-game, the game's image quality immediately becomes extremely dark and dim and largely unbearable, and even maxing out in-game brightness does not yield satisfactory results. My TV does appropriately report that HDR has been toggled off (the HDR logo "fades" in the top right of the screen), but the image quality in general tends to look way darker than any other SDR content I play.
So what I have NOT tried to do yet is try to disable HDR at the system level on the PS4 Pro to prevent any HDR signal to be sent to my TV. I did note that trying to restart RDR2, my HDR logo on the B7 turned "on" as I booted up RDR2 just after the RDR2 boot logo faded, but then the HDR symbol turned "off" (faded) when it started to roll the opening logo sequences. It seemed like the game's initial reaction was to attempt HDR output, even though I had it disabled in game, then when it recognized that my options had it toggled off, it tried to turn it off, albeit unsuccessfully as the entire image still presented in a very dark contrast that was unbearable, completely unlike the SDR result I had gotten on Xbox One X just a little while before.
So when I get home from work tonight, my plan is to disable HDR output at the system level on the PS4 Pro and see if RDR2 actually puts out an SDR image that's generally a match for the SDR output on Xbox One X. The latter is so far my favorite presentation of the game, overriding my previous statement in support of the "fake" HDR -- I theorize that if you're using an LG OLED and see the very dark contrast image when toggling HDR off in the PS4 Pro in-game menu, you'll need to disable HDR output at the system level on PS4 Pro to prevent what appears to be a glitch or TV error. If anyone else has also encountered this issue and already tested this, feel free to let me know -- or test it yourself if you have time!
On the Xbox One X at least, toggling HDR off at the system level does cause RDR2's image quality to improve in-game IMO, and I no longer actually hold the opinion that the fake HDR is still the preferable image output.
Also to note, sorry if this information has already been covered in another thread or in the new video that's in the OP -- I posted this having not yet watched the video. I'll edit a statement in if it's already covered.