-Seen
In cases like this, you should always let your gut feeling decide for you since it can take too long to notice that something is rigged. You can also take some snapshots or photos of that possible rigged website since they are using an un-hashed server. You can also test other websites Provable Fair algorithm.
What OP shared is more than a gut feeling! I agree with you Mezzaluna that he should provide snapshots, the name of the site, and
all other info that can help all of us, for some with technical knowledge to check their provably fair system, and for us others to avoid
that site. I don't check my bets, win or lose I just keep gambling, I trust Bitvest and other sites where I gamble enough to not do
it, but as we can see there're sites that cheat people.