I'm not sure how best to resolve this.
About a year ago, I donated $5, not realising (or maybe it wasn't clear at the time, or maybe I was just targeting that threshold for a number of games) that it was not enough to unlock the full game.
About a month and a half ago, I finally noticed the discrepancy and contributed $18, which unlocked everything. But it did so by creating a new transaction, and the Itch.io client, which I would prefer to use to not have to track updates manually, only shows the earlier transaction, for the demo version, and I've been unable to get it to resolve the new one after a number of time-separated attempts.
I am not seeking a refund or anything, just, like, guidance from anyone who may have gone through something similar before. Itch's support documentation suggests that a donation can be cancelled by messaging them or the creator, but that doesn't seem fair, at least without making the circumstances known.