Nigella (who only filmed her first series, Nigella Bites, in her own house) is very open about filming in a studio, but also says she essentially transports all her own kitchen equipment there for filming, as she prefers to work with her own things, and all her kitchen clutter around her. Which makes sense - I don’t know Nigella personally, obviously, but I do believe that what she cooks on her shows and puts in her books are things she genuinely makes herself. And as someone who cooks a lot myself, I get annoyed cooking in a holiday rental kitchen - I want my own things! (I genuinely take my own knives with me if we are driving somewhere). I also take my dog with me on holiday, obviously too, but taking it along as a prop for filming is quite funny. Meghan’s dog is obviously a lot calmer than mine!
So I don’t think it’s strange to hire or use another kitchen for filming - Richard Osman spoke about this in his podcast a couple of weeks ago - he made the point that you need a lot of space for a film crew and if you have a normal-sized kitchen, that’s a lot of inconvenience and bother. If you have a big house in the country - he specifically mentioned Mary Berry, and there was another tv chef he mentioned too - then you probably can film there more easily, and they apparently do.
I can also perfectly see that apart from the inconvenience you may not want to film in your own kitchen because it’s not the right aesthetic. Meghan’s trailer certainly looks focussed on using fresh ingredients from the garden (and apiary?) and so a light, airy kitchen with indoor-outdoor flow suits that vibe very well. From pictures we’ve seen, including her ARO reel, her own kitchen is darker - more Italian earthenware tiles and small windows and not so open to the garden.