Just to be sure, you're clicking the download button from your library, correct? The one under the heading "Things you own"?
NOT the download button on this page? And NOT the one from the new version update?
EDIT: I may have found the reason I had no issues; I "purchased the game on 2024-06-01 04:35:57 for $10.00" and thus any price increase under that amount doesn't affect me. Having enjoyed the free game very much before that, I had no qualms about paying more than the asking price.