Updated to Steam beta. Didn’t fix it. Tried SteamLink app on iOS and it has the same problem, so it’s not specific to Samsung TVs.
For me, Dolphin loads fine, but I tried a Retroarch game and it was just a black screen. Both games and BigBox look fine in the host PC, just not where it’s streaming to.
Attaching images because it’s hard to describe. Looks the same as your original post. I’d call it white washed, high gamma, something like that.