I know a guy who went to jail for that. He was in the news and everything. Banned from this country for life. Warned him that what he was doing was a stupid idea, he was even doing it for others who also got arrested...
I don't know what "that" was, and again, I had both the vaccination and the digital certificate to prove it; the system in place would not accept the real documents, so I fed it with other documents that it did accept.
The people who check your QR code with scanners on the entrance to a shopping mall (and refuse to let you in unless the scanner shows a green mark) are not the police nor the prosecution, and I have a good case to present to a judge in any case.
"The guy who went to jail" could be unvaccinated (or even infected) and presenting other people's certificates to enter an area for vaccinated people only (e.g. hospitals) where he might have endangered other people's lives; that's something that might be deserving jail time. I was vaccinated however, and by all means had the right to enter that shopping mall; I just wasn't able to prove it to the imperfect system that was there to check.