@Ratimov I dont think that those users will change their ratings now, but if the op can reach out to them and politely make a request, then its quiet possible that those users may consider changing their negative ratings to neutral.
One of them will never change anything.
It remains to wish this casino development and more positive reviews on this forum, then perhaps this red rating will not be so thrown into the head and cause unnecessary questions about whether this casino can be trusted.
It will serve as a warning to the players but seems they are doing a good job right now and although those ratings is provably cannot be taken out by the one who put out still duckdice management should do or continue their performance to get more positive reviews to their existing players.