To be fair, there were articles criticising her workshy ways (Duchess Doolittle, Willnot & Kannot), but since Meghan's arrival the Cambs have had overwhelmingly positive PR. Some bumps in the middle, but still. The tides are destined to turn sooner or later.
I have no doubt if she were working class that the media would be worse, though.
As
@Vanillaco points out, the palace PR machine is very well oiled: whenever a critical piece appeared in the papers, a counteractive article would appear in less than 24hrs, spinning all the criticisms of the 1st article as a positive.
Kate was coasting for nearly ten years, many people (incl me) have always said Kate would only kick it up a bit once Harry married due to the direct competition. Prior to Harry marrying, Kate was the only one in a particular position: young senior female royal. Barely anyone pays attention to the other working royals (eg Sophie, Camilla, Anne; Bea & Eug were always hated due to their parents, had an odd dress-sense, not "classically beautiful/pretty" and were always private citizens, never working royals).
Harry's wife would nill that and she did (regardless who she were to be). Turnt out to be Meghan, who, on paper, was far more accomplished than Kate: great uni, a degree, worked as actress (i.e. familiar with the media and has some training in that regard), had a blog, travelled, has written and given speeches. Seemingly a perfect fit (and as reported, Harry thought this would make it easy for her to transition into her royal role). How successful or apt she was is debatable and not the point, so please ignore that, it's a whole other argument.
Anyway, I have no doubt that Kate had some training in speech giving and all that, but look at her speeches and public appearances before ca. 2018 and after. It's like night and day. Even the first joint appearance of the 4 (Meg was still "just" a fiancee) for their then-joint foundation and you see the difference between the women: Meghan is confident, not afraid to speak ad hoc etc, Kate looks in some instances like she wants to melt into the chair, doesn't speak much, leaves it all to Will.
She barely spoke and the palace PR (to counter critics and questions) put out a story how Kate wanted to be like the queen mum: be seen, but not heard. Some of the quotes she said throughout the years were mindboggling ("can you smell the smell by smelling it" at Fortnum's) and her speeches badly read (like she read them for the first time whilst giving them, bumbling all the time) and not well written, either. Particular outrage when in one speech she basically blamed parents for giving kids an unhappy childhood and thus causing mental health problems, worded just as plumply as I wrote it here. Wasn't even packaged in a sophisticated manner.
After ca. 2018 Kate appeared a lot more confident, her giving speeches is a lot better. I think she took (again!) some lessons and finally took those lessons seriously and worked on herself.
Her recently sharing a handwritten note also reminds me of someone *ahem*.
Her wardrobe has also changed a bit since Meghan, and I do think that M has been a (positive) influence. Kate now dresses often in a more "professional (office worker)" style and carries actual handbags occasionally and not just her clutches. Some of her clutches were ridiculous, so freakishly small that you can't convince me she managed to stuff in there more than a tissue and a lipstick.
Meghan's influence on Kate (direct and indirect) is undeniable. I have followed Kate too long to not notice or attribute it to anything else.
Kate sugars won't like it, but either dedicate some time to look into Kate's work performance and wardrobe pre-2018 or live in your lalaland.
Again, most always assumed that Kate would finally step up once Harry married, regardless who she were to be and so it really was.
It was always said that Kate (and Pippa) is competitive and the direct competition of another young senior female royal did it, though sad that she only stepped up in her role and improved for that.
She was coasting as gf for nearly ten years, then she was coasting as royal and it took her nearly ten years to behave like a professional, now I assume it's gonna take another near ten years until she broadens her schedule. She seems to do things in ten-year spans.
I think Harry left for multiple reasons. For the reasons they claim and for the reasons the critics say are "really true", imo both sides are right on the money.
The Sussexes complaining of leaks from the palace smacks true, this has been an issue even in the 1980s and beyond (and for hundreds of years before!). There is plenty backstabbing there behind palace walls and it doesn't matter who it is you're going to backstab/who's going to backstab you, we've had PR wars over the decades between parents and children (I mean even Victoria and her son and heir Ed VII! this stuff is as old as time), siblings etc etc.
The Sussexes are problematic, too, and (Harry and) Meghan's leaked a fair bit as well, so if they're going to complain about leaks they should be fair and say that all the palace walls have holes as big as bear-cave entrances and that backstabbing is flavour of the day, every day.