The photo of her lower body looks like she could easily be a very small size, as you can see the muscle definition very clearly - she obviously does a lot of lower body working in lifting and I suspect she runs regularly, too.
I'm not as sure about her upper body shot, as it does seem to involve PS going by the change in background from textured on one side to absolutely smooth on the other. I vaguely wondered whether she's had surgery to tidy up and the use of longer sleeves and patterns to distract the eye and guide it towards her slimmest part - her waist - are part of that.
I think what they actually did was quote her largest UK size that fitted her bust as the starting point and the smallest size she can get into on her lower half as the end point - from ordering stuff online, I know you frequently have to pick US sizes for things from China, too - they might not say it's a US size, you go from the measurements in the size guide. I wouldn't be surprised if the 22 stone thing was when she was 9 months pregnant, either.
Whether she's had surgery or not, she's done amazingly well and I'd definitely be interested in the diet and exercise plan she had over and above that of somebody who has never had to make such a dramatic change of lifestyle, whether or not her 'supplements' were vitamins or weight loss medication. And stuff like this feature may very well be useful to her in setting up in business and becoming more financially independent, so if the press want to be slightly hyperbolic in the sizing, I can see why - I also think it might be a slight 'fuck you' to the ex, for which I applaud her, as it is so common that controlling partners are complete arses when their victims try to do something for themselves that might result in them being more physically attractive, healthier, more confident and less dependent/grateful for the scraps of attention.
I don't want to bring her down at all. None of this changes the fact that she went from supermorbidly obese to not in face of the end of her marriage and lockdown. She is incredible in how dedicated she has been and I hope if she does become a PT that her business does brilliantly. If I could do half as well as her, I'd be extremely pleased with myself.