many games in the second half of gen 8 struggled with performance on the base xbone (note I am talking about the base and not the xbone S, wherein the power gap is still smaller than series S/X). I will mention a few games that have bigger problems on base xbox one that came out recently - elden ring, far cry 5, AC valhalla. Even halo infinite - a game that has more right to be optimized for base xbox than most others - has some large frame pacing issues on base xbox one. I would have liked to use DF as a source but they stopped doing base xbone comparisons altogether in favor of bone S at some point. Series S is already a 30fps targeting system and that's a huge blow for me personally going into gen 9 where 60fps has become more of a standard or is straight up a standard.
Far Cry 5 was described by Digital Foundry as "a good experience" in an article literally titled "Far Cry 5 impresses on all consoles..." Assassin's Creed Valhalla had a pretty low resolution on base Xbox One but so did it on PS4 and all systems used temporal reconstruction to hit their designed resolution, frame-pacing wise it runs pretty well and has the same dips that are on the One X. Elden Ring is definitely an issue but so is the current Series X and PS5 versions, so I'm not going to put too much time into that game. I'll give you Halo Infinite but I think that game is overall just shitly optimized, even PC it chugs on moderately good systems despite its visual output.
If 30FPS is a huge deal for you, that's how you know the system isn't for you. It's for the majority of the console audience who played on base Xbox One/PS4 all last gen, even after Pro models came out because they don't care or notice lower resolutions or higher frame rates. They just want to play Fortnite, COD, sports games, etc... This doesn't change this generation. The average consumer who cares about those games isn't going to not buy an Xbox Series S because it runs at 900p instead of 1080p. This is gaming enthusiast forum where people really care about that, but in the real world no one gives a fuck. In a lot of games Series S has gotten 60FPS modes just like its counter parts. Hell it even has a bigger list of 120FPS games than PS5 currently.
when the standards of last gen drop, series S will be an afterthought for the industry while MS will be stuck optimizing for it since it's their product. This happened to the base xbox one and it's going to be even worse here. Being a 30fps product in the advent of a 60fps generation is already bad enough and it'll only get worse.
If it's a 30FPS product in the advent of 60FPS generation.... then its the perfect time to release a product like it. Games that run at 60 on the higher end machines can just run at a lower resolution and 30 on the Series S. This is literally the argument that Valve made with the Steam Deck, they said the Steam Deck should actually get more life because the consoles are targeting 60 which means Steam Deck will last a while targeting 30.