I hard an experience the last time I self excluded myself from an online casinos, very popular in my country and at that time I wanted to reconnect back later and the casino outrightly told me that my account doesn't exist, and when try to create a new account, it wasn't possible since their rejected my details anytime in insert them, since it has been used before, so most casinos that offers accounts deletion or self exclusion have a highly strict standing that prevents and exit the gambler from the casino forever.
It's the whole point of self-exclusion, isn't it. You don't want a user self-excluding themselves and then after sometime, they register on the platform, get a problem with gambling addiction or lose their savings, and then they start blaming the casino or even using them
I think you have seen such similar complaints in the forum, where some users blame the casinos for not helping them with their gambling problem when they tried to self-exclude. Such cases can lead to serious consequences.