How are these pdf's created? Does this happen with particular pdf file or all pdf files?
Are both computer systems on same macOS?
How are these pdf transferred? (some times data gets corrupted/tampered over transmission)
Please check if you have same issue in a different user / guest user.
Test with another user account
Also check if you have same issue in safe mode?
https://support.apple.com/en-us/HT201262
Note: Safe mode prevents your Mac from loading certain software as it starts up, including login items, system extensions not required by macOS, and fonts not installed by macOS. It also does a basic check of your startup disk, similar to using First Aid in Disk Utility. And it deletes some system caches, including font caches and the kernel cache, which are automatically created again as needed.