Reposting this since you posted the link to the outdated and misleading/confusing information again ;)
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Those who paid 10$ for access to A-files previously will no longer have access to the new A-files that cost 25$. They also cannot pay 15$ to get access, they would have to pay the full 25$ to regain access to A-files.
See discussion about this itch problem here: https://itch.io/t/4291978/raising-price-without-locking-previous-buyers-out