I did that when I created the account. Never stopped these mails.
But are the emails you receive from Itch or are they sent directly from the developers?
If you receive them from Itch and you have the options unchecked, then there is an error in the platform and it would be best for you to contact support and explain to them that you are receiving emails from them, even though you have the option deactivated.
If the emails come to you from accounts outside of Itch, then it is complicated, when you buy, the email of the account that buys appears in the seller's sales summary and if there is no centralized way to avoid these emails here, it would be best for you to contact support and send the emails you are receiving and explain the situation in detail, to see if they can do something.
To contact with support:
https://itch.io/support