The PS5 figure is a tad strange but not out the ordinary, I suspect that the power gap between the Xbox Series and PS5 will continue to widen as we get more games that are developed for net generation console hardware. I wouldn't be surprised if it turns out the X version of the game is 4k 60fps.
But we also need to be reminded that Sonic Team has a terrible track record for optimization going all the way back to Sonic Heroes released in 2003, which is also coincidentally the best selling Sonic game in the last 19 years. Any time a Sonic Team major Sonic release seems to be technically competent it's usually because they compromised somewhere. For Forces there were many rail segments where you don't have much control of the player, and it went hard on automation and cool visual set-pieces which taxed the engine so you ended up with several small levels, the shortest levels in any Sonic game.
Here, the game doesn't look like much, passable but not mind blowing graphics, many empty patches between enemy encounters in the "open-zone" lots of resued assets and repeating animations, and the cyber stages from what we've seen so far outside of the tutorial stage which was lifted from Sonic Unleashed with a new coat of paint, also look like they are derived from Forces level design. We have also seen automation in the open zone from puzzle solving to exploration, that tall monument comes to mind.
With this, it would seem odd for the PS5 to be 1080p in order to reach 60 frames, however if the engine is unoptimized you'd likely have to have a lot more raw power to cut through its short comings and in this situation I can see the PS5 falling short on dealing with that.
About the game, I'm still concerned about several of its gameplay mechanics, the cyber stages and their lack o branching and automation, and the combat. They have still refused to give us longer videos breaking down these things less than 2 months till launch and so far we've been shown selective gameplay that tries to mask the issues from the IGN videos that haven't ever been fixed or addressed in any build shown or leaked.
Is this combat going to be good? is it filled with useless moves that are only there to pad-out the moveset? Are the enemies damage spongers, am I gong to be repeating the same moves over and over because it's the best way to fight off enemies and bosses? Are they going to do anything to make all that empty space seem full? Are enemies going to be scattered unto a giant empty space? How much of these hubs or cyber stages will be automated? Why did they add Big the Cat fishing to the game knowing full well it was not favored in SA1? Are the puzzles in the open zones going to be interesting with new ways to approach them and not feel like busywork, or will they end up as has been shown so far, slow, Sonic Boom tier, bland puzzles just to fill up game time?
More importantly the grinding, we need to know what's going on with that. How much time do you need to become stronger and to progress the game? How much time do you have to grind and/or collect things in order to move forward or effectively deal with bosses and get access to the cyberstages? This is going to be a long game with over 20 hours of playtime, but if that 20 hours is due to slow puzzles, grinding, and collecting that doesn't sound like a good time.
These questions have never changed, and Sega has not bother to address them. You then have to consider that if a lot of this isn't fixed or is worse than they seem, worst versions of the game will makes these things even worse, the switch for example.