The article says: "While almost no modern applications read these AF and PF bits"
It can't really be legacy software, as most AMD64 software on the Mac is fairly recent (2006) and I suspect that we're talking software older than that for the AF and PF to be in regular use. So it also have to be something fairly important like virtualization or something used in image processing or compression. It seems like overkill for something that would be a problem for an end-user application that would transition to Apple Silicon anyway.
The article says: "While almost no modern applications read these AF and PF bits"
It can't really be legacy software, as most AMD64 software on the Mac is fairly recent (2006) and I suspect that we're talking software older than that for the AF and PF to be in regular use. So it also have to be something fairly important like virtualization or something used in image processing or compression. It seems like overkill for something that would be a problem for an end-user application that would transition to Apple Silicon anyway.