If the doorbell camera was facing into the outside, then I am not sure what grounds the tenants have to complain. Hotels and apartments can and do monitor public areas.
Well the camera aren't the tenants property so putting something on top of them like tape would be simple vandalism. They can always obstruct it without touching it.
I can't imagine that a tenant temporarily obstructing the view of a security camera qualifies as simple vandalism in my country but maybe you live in a different place.
If that's the case then merely standing in view of the camera would qualify as vandalism as well because you'd be obstructing the view of what is behind you.
The Airbnb rules for hosts: If you’re a host and you have any type of surveillance device in or around a listing, even if it’s not turned on or hooked up, we require that you indicate its presence in your House Rules. We also require you to disclose if an active recording is taking place.
Is there some sort of law or rule obligating tenants to keeping the view of cameras unobstructed?