I tried Googling to find this blog post. Did you mean to write Yarden Shafir? If yes, maybe it was this blog post? https://windows-internals.com/printdemon-cve-2020-1048/

I also found another hint about their findings in this PDF written by Yarden's co-researcher Alex Ionescu: https://www.usenix.org/system/files/woot20_slides_ionescu.pd.... One of the slides specifically mentions the use of fuzzing tools to find these issues.

If there are other, better links I don't know about, please kindly share. :)