Cruella sucks, but it sucks in a way that's way more complicated than "funny dog kick mom off a cliff".
For instance, it's not a movie about why she hates dogs. Cruella de Vil doesn't hate dogs. She has a dog who's been her friend since she was a child. She does kidnap the Dalmatians that killed her mom, because one of them ate her mom's family heirloom necklace, but by the end of the movie, she's won the trust of the Dalmatians and they're her pets now.
Or, for instance, the movie turns the name "Cruella" into a deadname metaphor. See, when she was mean as a child, her mother told her "You're Estella, not Cruella," so Cruella spends the first half of the movie trying to make her mother proud by repressing her "Cruella" side. But then she learns that her actual birth mother is an evil narcissistic fashion designer. This is presented as the reason why Cruella has an evil narcissistic side, and why she's a good fashion designer: because she inherited talent, narcissism, and evil from her birth mother. Her foster mother was therefore wrong to try to change her. She decides she's never 'really' been Estella, and she is now Cruiella. The movie even ends with a funeral after "Estella" fakes her death and she has completely adopted being Cruella.
Or, for instance, the whole thing is a seventies period piece, ostensibly set before the plot of the original movie. The original movie came out in the sixties. There was a live-action remake of the movie made in the 90's (and set in the nineties; Roger Darling was a video game developer instead of a pianist) starring Glen Close, who has an executive producer credit on this movie. But there is also a Roger Darling in this movie, who is a lawyer who gets fired and becomes a pianist so that the post-credits scene can be him doing one verse of the Cruella de Vil song. So it's not connected in continuity to either of the 101 Dalmatians movies.
Also, while the movie has a lot to say about classism, it features zero racism, in a high fashion setting in London in the seventies. It is conspicuous and deliberate about putting non-white actors in visible roles, which normally I have no problem with, but at the same time it's hitting the '70's period piece' thing as hard as possible. So it ends up feeling like a weird sort of historical revisionism where they wanted the "realism" of setting this in an identifiable location and time period, but dealing with seventies-era British racism was uncomfortable so they just skipped it entirely.
Also the character that was touted as the first openly gay character in a Disney movie (that's a live action prequel of an animated Disney feature) is a camp gay stereotype named Art ("as in, Work Of," he explains) who owns a twee thrift shop, wears asymmetrical eyeliner, bonds with Cruella over fashion show trivia, and is on screen for approximately 5 minutes. I don't recall them ever bringing up that he's gay. In his last scene he has zero lines and mostly stands around in the back of the shot looking confused.
Despite all of this, it's still okay. You can watch it and it'll amuse you for two hours, it just has very little in the way of substance and as soon as you start digging it's just Disney-brand narrative rot. Anything that one could get out of it you could just as easily get by watching The Devil Wears Prada, Sweeny Todd, and dealer's choice of Wachowski movies back-to-back, and then you'd have watched three good movies instead of one mediocre one.
As best I can tell, the movie is directly aimed at teenage theater kids, so if you're not currently in your high school's drama club, there's not much for you in there. It's wall to wall high camp melodrama that's utterly toothless because its most coherent message ("classism bad") is undercut by Cruella turning out to have been a temporarily embarrassed aristocrat.
