A possible alternative - and I'm categorically not saying this is true, not even likely - is that Covid19 is more infectious, and more widely infected people. B

A possible alternative - and I'm categorically not saying this is true, not even likely - is that Covid19 is more infectious, and more widely infected people. But, that fewer people were susceptible, so there would be more asymptomatic carriers but fewer people hospitalised. If a virus runs out of people to infect then it will peak. You can prove that scenario wrong by testing (if number of 'already infected' is relatively low then this hypothesis would be wrong and the risk of further peaks is higher; I don't have enough data to attempt to disprove such a hypothesis.