Windows 8.1 is still supported by Microsoft, with security updates provided until January 2023, so it's not dead.
I just installed Acrobat DC Pro on a Windows 8.1 PC and it installed the known vulnerable version 220.127.116.111 Adobe Creative Cloud Desktop along with it. Adobe says Acrobat DC Pro is supported on Windows 8.1, so what does Adobe mean by supportedif they install known vulnerable software with it that appears to have no available security update? Add to that the recent APSB21-18 that adds three more unpatched CVE's to Adobe Creative Cloud Desktop.
What am I missing here? Does Adobe support Acrobat DC Pro on Windows 8.1 or not? If they do, then what does Adobe mean by supported?