As was reported, the Steam Deck OLED comes with SteamOS 3.5 preinstalled, while the stable channel is still on 3.4.
This means if reviewers didn’t take care to properly match the software versions on the OLED and LCD models, they might not compare apples to apples. The effect is probably small, but so is the reported performance and power draw difference between the models. Also SteamOS 3.5 introduces the saturation slider which in its default setting tries to emulate sRGB more, and could affect screen comparisons.
See for example Taki Udon’s first video, where clearly it is visible that MangoHUD is an older version on the LCD model https://youtu.be/3C6ekDyO18s?t=807
So unless it is explicitly mentioned or shown otherwise, assume that part of the differences might be due to different software versions.
The LCD can literally only cover 70% of the very basic sRGB color gamut. The saturation slider in SteamOS 3.5 does not “correct” this problem. The OLED screen is not better because the saturation slider is cranked up. It’s better because it covers 100% of sRGB, 97% of DCI-P3, is capable of 600 nits in SDR, and 1000 nits in HDR. It has per pixel dimming allowing it to have infinite contrast. OLED pixels transition between colors effectively instantaneously for the purposes of a gaming discussion.
These two things are simply incomparable regardless of the version of SteamOS running. The LCD appears pale to the eye without the Decky Loader plugin because it cannot generate the necessary colors. Cranking up the saturation makes the colors it can generate appear more vibrant but wildly inaccurate.
Jokes on you, I’m colorblind