Sick bag provisions have been sporadic at best even prior to Covid.
There should be at least one in the seat pocket, and cleaners aren't required to change unused ones after each flight.
If there isn't one, there are usually additional supplies in the lavs in a pull-out stowage, or the crew should be able to find a couple knocking about somewhere.
It is something that crew have raised to the company on a number of occasions though.