People are moving out but not in. Move-ins set the rental rate. A lot of people are leaving for lower cost areas or to move in with family.

Not everyone is stuck at home with no income. If I were working in the Bay Area for a company that was still doing ok, and I were already planning to move around now, I would definitely see this as an opportunity to get a good deal on rent by moving. Maybe some other people are thinking this. Or maybe they are thinking that there is no point moving elsewhere in the Bay Area and are moving further out.

Though I would certainly expect the number of transactions to decrease a lot.

Up until the new modified shelter in place orders, you couldn't move unless your lease expired or you already had the move planned. Also moving companies were allowed to stay open if they provided their movers with PPE, so many chose to shut down.

So for the most part people just couldn't move, even if they wanted to.

But if few people are moving anyway (for reasons above) then it doesn’t matter if there are fewer moving companies because of the above. Obviously some people are moving or the OP wouldn’t have been written