I think what we are all seeing are The Muppets moving away from their original selves. I do not think this is an issue with the performers, but an issue with the writing and creative direction. Whoever is writing for these characters does not understand them. Not to turn this into a character analysis thread, but let's look at a few. (prepare for a LONG post)
Scooter
Scooter, up until his full return in The Muppets 2011 (though he had some minor returns prior) was characterized as an opportunistic suck up. He was always looking for ways to make a buck and use Kermit's authority for his own gain. If he wanted to do something all he had to say were those five little words "My uncle owns the theater". Sure, he followed Kermit's direction, but he did so in the way one would follow their boss's direction. Do what your boss says so that he keeps you around and as he moves up, you move up.
So what has Scooter become? Well, in The Muppets 2011 we see him as Kermit's stage manager, but he is far more good natured. He follows Kermit's direction, not to advance or get what he wants, but because he looks up to Kermit. When he calls Kermit "chief" it sounds a bit too... genuine. He seems genuinely concerned about the show, not his own career. There is no side hustle or scheme or sucking up to the boss. He is just mild mannered friendly Scooter.
In The Muppets 2015 this goes way too far in the nerdy direction. He lives with his mom, he is scared of everything, he is now afraid of losing his job and seems to have a genuine fear that Kermit will can him. Not only his is not looking to use Kermit to advance, he seems to never want to move up and wants to remain in the shadow of Kermit because it is safe. He turned into what Muppet Babies Scooter would have turned into, but was no longer what Scooter started as.
Now we see what looks like a mix if The Muppets 2011 and The Muppets 2015. He seems afraid for his job and good natured, but seems to have lost the ultra wimpiness he was given in the 2015 series. He is just... there.... Sure, it is nice to see him and he serves his purpose, but it isn't really Scooter as we knew him.
So how should Scooter be modernized, in my opinion? Make him an intern who has multiple side hustles. This is the gig economy after all. Scooter interns for Kermit in the hope of landing a steady paying job (which could be a running theme that Kermit does not pay him), but a point of conflict is that Scooter often abandons his post to be an Uber drivier, or a dog walker, or he because he just got a task rabbit job. Kermit now keeps him around, not because his uncle owns the theater, but because he is the best help no money can buy. This would be a return to the Scooter that is always looking to make a buck, keeps conflict between Scooter and Kermit, and gives both of them a reason for Scooter being there.
Swedish Chef
Chef has always been an odd ball. His main purpose is to deliver food related puns, usually by his very literal translation of recipes. He is a one note character, but that one note relies on clever word play. He hasn't changed too much in terms of character, but he has become far less clever over the years and in Muppets Now he seems down right dumb.
In this episode, we see Chef just being kind of lazy and stupid. They do the gag where he drops the entire box of salt in the pot, but usually when that gag is being done the Chef is... ya know... cooking something that he is seasoning. Usually the gag is someone is cooking a dish, they add a little salt, taste it, add a little more, taste it, then they dump it all in. This same gag goes for hot sauce, sugar, etc. In this case, they do an over head shot showing nothing in the pot. He is just putting salt into an empty pot... then throws the box in, The over head shot does not work for this gag and the context doesn't work either. They some how took a lazy yet mildly funny gag and they made it lazier and unfunny.
Then we see Chef add in seemingly random ingredients that had no clever word play attached to them. He throws in popcorn, cherries, a whole onion, a pineapple, there is no rhyme or reason. The other cook uses a pineapple in her dish, but not at this point in the bit so there is no reason for it to show up yet. Eventually we see a chicken and he is massaging it, but instead of doing a tenderizing joke, they say marinating? That doesn't make sense... Maybe if he was giving the chicken a bath, or if he got out a kiddie pool to put the chicken in, or even if he made a cocktail and had drinks with the chicken. Then maybe that joke would make sense. Otherwise it seems like an improv joke that didn't make sense, but they used it anyway.
Now we come to the plantains. We get a cute word play where he thinks plantains are plants or "planties". At least it makes sense in context. And then Chef just starts hitting bananas with a mallet... Why? The joke here is just "Chef makes a mess". Nothing clever. Finally, he just orders some food online. Not bad. Then the joke is ruined when he smashes the bananas and dirt on top of it.
Essentially, the writers took a character that was one dimensional, but relies on clever writing and removed the clever writing. This is the problem with Muppets Now being an improv show with only a guide instead of a script. Other characters can talk their way through an improvised bit. Chef can not. His whole shtick is literal interpretations of recipes and/or sight gags with violence like when his dough attacks him or lobster banditos show up. The only way to save his character is to actually write for it.
Perhaps, in this case, they could have made "jerk chicken" and the gag could have been that the chicken was a jerk. Or they could have stayed with curried chicken and played on the steps to make it like doing a spice rub (which ALSO would have worked better than saying marinate when Chef was massaging the chicken!). The could have made the chicken a "courier" to play off "curried" chicken. They could have said "spice your chicken" and instead Chef "spikes" the chicken like a volley ball. Basically anything other than random unrelated nonsense. The Chef is funny when he is literal, violent, and misinterprets things. He is not funny when he is doing random things just to be random.
phew... I think that is enough for now. I was going to tackle Piggy, but there is so much to unpack there that I think she will need her own post. In short, The Muppets need writers that actually know what made these characters iconic to begin with and not rely on surface level material. Seems like some of these bits were written based off of what the general public, who is not a Muppet fan but only has a passing familiarity with them, thinks these characters are.