QR code can be generated with different styles, . It's the geometric shape that matters, I've seen QR codes with red background and white lines work just fine; actually, look up that AI generated QR code thingy where the code is embedded inside a colored image, which can be a person, scenery, or whatever else. The open-sourced QR code generator alone supports several color schemes.
If one has to tattoo QR codes on their body, and they have dark skintones, just tattoos the bars white. But I fail to see why since most QR code provided by payment services expire in a rather short period of time for the specific reason of theft protection. Only payment codes can be permanent, since, ya know, money can going go in the account of the QR code owner in this case.