Even so, that mechanism is basically subscribing people to a mailing list without consent and no ability or even information beforehand. The information that is given is the setting about notifications of bought items, but this setting does not apply to these emails.
There should at least be a button on the individual purchase page to unsubscribe and information about this mail subscription on the purchase page and in the purchase confirmation mail. Since you do can unsubscribe from those lists, they are obviously not deemed important anyways.
On the purchase page is only the follow button. But no trace of a hint, that you are also subscribed to such a mailing list.
I would like to point out this portion of the faq.
https://itch.io/docs/creators/faq#can-share-the-information-itchio-collects-abou...
Do not automatically sign up people for mailing lists. If you'd like your buyers to sign up for your list then you must get explicit consent from them.
Yet itch does sign people up automatic, with no consent, no information.
While you do try to clarify...
The email address that itch.io provides, along with the email tool, are made available if you need to contact buyers with news related specifically to their transaction.
... I wonder what % of the mails OP received were of that nature. The way the complain was made, I dare say, near zero.
Maybe this is translation issue, but "need" implies urgent matters and not trying to share news. That should read "want" instead, if it were meant for the use case mentioned elsewhere in the faq, about informing about updates and suggesting to me, that this feature is obsolete mechanism of early itch days.
You should seriously overthink how this feature is implemented and communicated to buyers. Currently it comes out of the blue. OP did not even realize why those mails come.
Also, how would you re-subscribe to an unsubscribed mailing list?