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.
Something most people AREN’T talking about is the persistence of the display; although it isn’t too bad; the Steamdeck LCD display has noticeable “ghosting” that on the OLED isn’t present. This is called “Motion clarity” and the oled steamdeck should be a massive improvement on that front.