Our district has no official regulations. We have been rehearsing inside, and we're split across the limited space we have, but that still doesn't get us 6 feet apart.
It hasn't caused a COVID increase, but on the occasions that a band student tested positive, they did send the students who sit within 6 ft of them in band home for risk of exposure. None of them ended up testing positive, but it was taking out several students so we shut down playing operations for a couple weeks. We're back at it now with one room being a distanced sectional room and the other being a theory/music activity/whatever music related thing I can find for them to watch room.