I mean, it could not be that big of a security issue considering that the attacker only forces the printers to print that text and do nothing else, but the mere fact that people can gain access on a printer surrounded by tight systems is pretty much a sczry thought on itself.
If they can force a printer to print a file, it means they are able to send the file to the printer to be printed. In some cases, and with the right file, being able to send a file to a printer is enough to be able to remotely execute malicious code (example:
https://nvd.nist.gov/vuln/detail/CVE-2018-5924). Obviously printer malware could steal the details of anything being printed, including paper wallets, but it can also use the printer to propagate malware through the network and infect other machines with anything from clipboard malware to ransomware. Although it is improving, many network capable printers still have little or no in-built security. It's probably not a big concern for the average user, but it can be a serious vector of attack against businesses and corporations. If you are concerned, you can pick up an old school wired printer for ~$20.
It's a cheaper solution compared to a hardware wallet and does any other things apart from just being a hardware wallet, too.
You should be careful doing anything else on the device which is storing your crypto. It should be permanently air gapped, and you should also be very careful plugging it in to any external devices or using removable media such as USB drives, as these can be used to transfer malware. Ideally, you should use it for crypto and nothing else.
