Mine covers that differently for the third party insurance vs the bits I could claim.

In case of gross negligence, for third party claims against me the insurance covers them - this is probably a legal requirement, otherwise the insurance is a bit useless as you could argue many accidents are grossly negligent. Also they reserve the right to sue me for the money.

Not surprisingly, if I'm grossly negligent I can't myself claim - e.g. if I leave the brake off and the car rolls into a wall, they'd pay for fixing the wall but not my car.

But going out during quarantine would not be any sort of (car insurance) negligence because it has no bearing on the vehicle or driving. It would only be negligence if the insurance was against infecting someone.