A lot of reviews seem fake and are praising the product. There are the odd 1 or two who are rightfully calling it out as a fake product and the seller not refunding the purchase.
It goes without saying. We have not genetically modified rainbow tomato and they do not exist.
More importantly, I find it hard to believe you could get multiple tomato colors on one plant. Then again I really know nothing about tomato plants so ¯_(ツ)_/¯