I watched a couple of her shows and the stuff she made seemed weird (wish I could remember a couple). Mixing ingredients I'd never in a million years put together. I didn't enjoy them as programmes.
With the exception of Nigella (who I'm also not a fan of), I think almost all other chefs on TV are exactly that - chefs. Trained and experienced over many years cooking in, running, and often owning restaurants. For someone who won a TV baking competition Nadiya has had a very good run, far more than the usual ten minutes of fame.
The BBC stop making programmes for four reasons: 1) they cost too much to make. 2) the ratings aren't good enough. 3) the presenters have done something they shouldn't. 4) the format is tired and it's time to go in a different direction.
I think to automatically cry racism when they've employed you to make umpteen series over many years is pretty disingenuous.