Can you take off your mask when you show your QR code?

The mask is back after not being gone for very long. I had hoped we could have put it in a time capsule to show it to our descendants later when we talked about this period, but unfortunately. It is back in full swing. And, entirely in the already quite rich corona tradition, there are again questions and uncertainties.

At the physiotherapist, you don't have to wear a mask, but at the masseur you do.
And there is indeed a reason for that, because the physiotherapist has a medical profession and may ask you medical questions from which it appears, for example, that it is better for you to be treated without a mask. Your masseur or hairdresser or nail stylist or anyone else is not allowed to ask you about your medical condition (they do ask me, by the way, but that's beside the point), but you must always keep your mask on.

They are not allowed to ask about your medical condition, but they can send you away if you have a cold.
Are there exceptions that do not need to wear a mask? Yes, if you cannot wear a mask for medical reasons because you are, for example, asthmatic or have a mental disability and therefore become disordered. You may need to demonstrate this to an enforcer by showing a letter from your doctor, for example.

Then there are still the occasions where you need to show your QR code, such as museums. Do you still need to wear a mask after you have shown your code?

The answer is: yes. At least, I believe so, but please don't hold me to that.