We should be careful to only set tags that correspond to signs or other verifiable information sources. I bet there are no separate signs for pedestrians, cyclists and motor vehicles. Maybe one sign for vehicles (Fahrverbot) and one for pedestrians. Are you sure that the entire area, including "Erholungsgebiet Steinhof" and the museums, is shut off for people without a covid test certificate?
We might consider access=permit, because a covid test certificate is similar in spirit to a written permit.