Apple has a lot of shit they need to fix in macOS and the accompanying apps.
That said, the author of this article is clearly an ass, and i have a hard time being sympathetic.
Assuming the pdf is actually in spec, which it's probably not, this shouldn't be happening. That said, if the 3rd party app vendor says the pdfs they generate are broken in big sur, that should tell you, they may be broken other places as well, and it's probably not apple's issue.
That said, the author of this article is clearly an ass, and i have a hard time being sympathetic.
Assuming the pdf is actually in spec, which it's probably not, this shouldn't be happening. That said, if the 3rd party app vendor says the pdfs they generate are broken in big sur, that should tell you, they may be broken other places as well, and it's probably not apple's issue.