Is it possible to save visibility states of collections in a view layer in such a way that they would be restored when re-activating the view layer, even if the visibility states have been manually changed while the view layer is active? If you control visibilities using the "Exclude from View Layer" check box, that change of setting is stored in the view layer. When working on a complicated scene, one may need to use the Exclude selection a lot when editing objects, and then revert to a previously saved setting of visibilities.
You can use the "Local Collections" in blender 2.81. They can work per ui window and not per view layer. Go to the "N" Panel>View>Collections, check "Local Collections", and toggle visibility with the eye icon.
You then uncheck "Local Collections" to get back to the previous state.
Alternatively you could duplicate the view layer in the initial state, and then go back to it once you are finished tweaking your scene in the other view layer. The duplicate icon is in the top right corner next to the "remove" icon.