Just want to point out that the solution on removing and reinstalling printer-driver-cups-pdf didnt worked for me on my buster system which i upgraded from stretch. i have this issue since then and was happy to find this solution which unluckily didnt work for me.
i managed to find a very old print job in the pdf qeue which maybe the cause for this failure in the update process. "cancel" this old job and repeting the solution didnt work either. so i followed the advice in the debian wiki https://wiki.debian.org/CUPSDebugging and issued "lpadmin -p <print_queue> -o pdftops-renderer-default=pdftocairo" to the (in my case named) queue "PDF" that solves the problem. lpoptions -d PDF shows the correct output and the printing is as expected. thanks to neil and brian who directed me in the right direction :-) kind regards steve
