Personally, it is completely not ideal to leave funds on the casino, anything can happen and the funds will be lost even with 2fa active on the account.
We've seen a case on this forum where a user left over $200,000 on his gambling account, He has 2fa activated and felt he was safe enough, but unfortunately, his account was hacked and the money stolen, the hacker probably gained access to his email account as well, and with that, he was able to deactivate the 2fa, then he registers another account on the same casino and used the internal transfer feature to transfer the money to the new account, and from there, he withdraw it out of the casino..
Best practice is to never leave tangible funds on the casino, even if 2fa is activated.
This case is very specific, but I have heard of different cases where you cannot leave the money funds because some casinos, if they do not go to them, can lose the money, something like that if they do not have activity, they suspend the account and obviously, they keep the money that was there, I saw that in a thread here on bitcointalk, which I thought was in very bad taste, because it makes no sense to do something like that, I know that when money is left on a platform, that money no longer It is our fate of the site, but even with all that they must respect that sense of belonging , I see it as something very legal.