1) If there is any game that runs well on UE5, that shows UE5 isn't the problem.
2) Devs don't have to use features of an engine if they don't run well. The fact a game engine can scale up to uber levels doesn't mean that needs to happen. Use UE5 and use baked lights instead of Lumen - that's an option. Nanite too demanding? Don't use it. Use the same techniques used prior to these techs. If devs throw too much at a game, it'll crawl on any engine. See Crysis 2! UE5 was not created just for consoles, but for many platforms including scaling up to ultra PCs (and even driving Hollywood FX), but taking an Uber PC game and sticking it on consoles isn't going to work well.
Yes and no. If it's because the devs aren't managing expectations and are throwing all the pretty bells and whistles because it makes for gorgeous screenshots that drives early interest, that's on the devs. And that's what a lot seem to be doing, chasing the 'next gen' look even if the hardware isn't up to it. "Wow check out this lumen! that looks great. Woah, see this Nanite geometry! Amazing, let's get that in there. Okay, let's build for console...oh"
UE5 provides plenty of flexibility to use different techniques. That moves the onus onto the developers to choose wisely, and it seems a lot can't. But we know this. The moment 'post processing' became a thing, we got excessive brown-o-vision, bloom and chromatic aberration. These were layered on with a trowel just to ram home that 'next gen' look. Give devs some amazing lighting results and geometry options and they'll pile it on and then step back and admire their visuals, ignoring the framerate. This isn't anything new. There were plenty of 20 fps games on PS2, pushing the graphical (or gameplay) features beyond the hardware's ability to run them at a decent framerate.
So going back to point one, where you say it's UE5's fault, the existence of one game that uses features and runs well proves it's not an engine limitation. The engine can run well, also using high end features. Either design your game to fit the features so they'll run well, or pick the features that'll run your game at the preferred framerate.
We can only point to UE5 being bad if there are other engines achieving the same visuals/features at better framerates. In the absence of that, there's no evidence other than circumstantial that UE5 is dodge, and that's not a logical nor fair conclusion to jump to.