General Discussion

It's when they have been replaced (like with a sticker) or the poster or whatever has been made by scammers, that there's a problem.

If it's a manual, as someone said you can search the product and model name, or look for the manufacturer's website address and look on the site under Support or product manual or similar.

Another option: If you are using a mobile phone, just use a separate app to scan the QR code. I use this one, but there are many:
https://play.google.com/store/apps/details?id=com.gamma.scan

The app then "translates" the QR code to a URL (web address) without opening the website. You can decide at that point whether or not to open that URL in a browser, using one that doesn't allow tracking if that's a concern.