They are exempt. It's "2g" rules (geimpft, genesen), so you can have had it or be vaccinated. For clubs and similar they're introducing 2g+ which means you also need a PCR test.
I had an experience like this in a parking lot in Belarus: our van wouldn't react to the keyfob. A man soon came by offering to help for some money, but some others warned us he was using some kind of jammer to make this happen on purpose.
In fact I think it wasn't specifically made to be a jammer, he was just trolling with an accidentally-discovered device causing interference