I know anecdotes aren't data, but I would not be surprised if this was hitting close to the truth.

I had a friend who had RA starting in her teens and was on very heavy medication for it, with no real hope of improvement. In her mid-20s she changed her diet significantly -- I think she went gluten free, maybe it was some other restriction. I thought it was silly TBH, why would changing what you eat affect arthritis?

After about 6 months her RA was entirely in remission and she was off all of her medication. As far as I know has not recurred. I can very easily imagine that dramatic diet changes affect the gut biome and could have tipped the scales to make her gut less hospitable for specific causes of RA. I hope so!