Gambling sites have a common issue that if any suspicious behavior is detected, the account may be subject to KYC issues. Winning 100 times your bet after joining a new gambling site can certainly seem suspicious. But yes there is nothing to fear here if the gambler fills his KYC details with correct information. But of course here I should check if the site I am registering is reliable or not. A new site can be a little risky if that's the case. Moreover, the matters related to KYC which are mentioned in terms and conditions should be carefully observed in advance. A gambler must be thoroughly observed for safe gambling.
The casino will immediately check the gambler's account who can win 100 times the bet and ensure that the gambler has not committed any fraud. Later there is a possibility that the casino will ask or ask the gambler to carry out KYC before the gambler withdraws his money. This is to ensure that gamblers do not cheat and are not involved in other illegal things that could harm the casino. For this reason, the casino may be too strict even though the casino is only carrying out the procedures given by the regulator to keep the casino safe. But that will not happen in shady casinos because shady casinos only want your money and your identity for other purposes.
If you're gambling on a legitimate gambling platform and they flag your account just because you've won multiple times without doing anything, then you might want to check the casino again. Usually, they only flag new accounts after winning so much due to the amount they've won and due to regulations purposes they require their user to follow through the KYC process.
Anyways, I've experienced winning a significant amount after losing my bankroll and was given some tip from chat from someone who is a highroller and was able to get it up to atleast 500-700$ at that time and was able to withdraw without any trouble.