Hmm, aus diesen Leitlinien:
3.4. Right to compensation
Regulation 261/2004 also provides for fixed sum compensations in some circumstances. This does not apply to cancellations made more than 14 days in advance or where the cancellation is caused by 'extraordinary circumstances' that could not have been avoided even if all reasonable measures had been taken. For details, see Article 5(1) and Article 7 of the Regulation.
The Commission considers that, where public authorities take measures intended to contain the Covid-19 pandemic, such measures are by their nature and origin not inherent in the normal exercise of the activity of carriers and are outside their actual control.
Article 5(3) waives the right to compensation on condition that the cancellation in question “is caused” by extraordinary circumstances, which could not have been avoided even if all reasonable measures had been taken.
This condition should be considered fulfilled, where public authorities either outright prohibit certain flights or ban the movement of persons in a manner that excludes, de facto, the flight in question to be operated.
This condition may also be fulfilled, where the flight cancellation occurs in circumstances where the corresponding movement of persons is not entirely prohibited, but limited to persons benefitting from derogations (for example nationals or residents of the state concerned).
Where no such person would take a given flight, the latter would remain empty if not cancelled. In such situations, it may be legitimate for a carrier not to wait until very late, but to cancel the flight in good time (and even without being certain about the rights of the various passengers to travel at all), in order for appropriate organisational measures to be taken, including in terms of care for passengers owed by the carrier. In cases of the kind, and depending on the circumstances, a cancellation may still be viewed as “caused” by the measure taken by the public authorities. Again, depending on the circumstances, this may also be the case in respect of flights in the direction opposite to the flights directly concerned by the ban on the movement of persons.
Where the airline decides to cancel a flight and shows that this decision was justified on grounds of protecting the health of the crew, such cancellation should also be considered as “caused” by extraordinary circumstances.
The above considerations are not and cannot be exhaustive in that other specific circumstances in relation to Covid-19 may also fall under the ambit of Article 5(3).
https://ec.europa.eu/transport/sites/transport/files/legislation/c20201830.pdf