I don't know how the Covid regulations work where you live @Jolin0 but as you say most sensible people are minimising their travel during Covid. (I thought California was under lock down too)??
In the UK it was illegal to host all but essential workers from March to July and we just came out of lockdown in England on 4 July.
Sounds like if you are choosing to host guests during a period of restricted travel in your location, that you would be better vetting your guests before agreeing their stay to understand the purpose of their trip and why they chose your place to ensure there is a good fit.
What sort of spot checks do you make with your cleaning company? Do they send you dated stamped photos of each room when their cleaning is complete?
Sometimes we think a supplier is doing a good job because they have done so in the past. But we need to have systems in place to ensure continued good quality.
I agree with @Anonymous respond to bad guest reviews calmly and professionally addressing points raised, so future guests can see you have taken issues seriously.