Of course they read everything. They return documents for missing check box, so they look at every small detail.That seems implausible.
1. Why would they prioritize those? Citizenship does not give you any advantages over PR except you cannot vote, be elected, and work on jobs with top secret clearance.
2. How would they even do this? Would they read through all paper applications to find people who work in essential services on a year old applications? What if they do not work there anymore? What if they did not work in essential services when applied but work now?
3. There would be some sort of communication from the CIC regarding that
I don't know how they keep track of people's workplace. Maybe they keep track in the system or something.
It is possible that people even die during the process, however sadly it sounds, not only change jobs. But did you know they freeze data in application when they receive? Example: you are 35 y.o and you get max points for age for immigration. Even if process takes many years and you get old, you are still considered 35 and get max points.
And lastly there is a communication from CIC, although not explicitly for citizenship.
https://www.canada.ca/en/immigration-refugees-citizenship/services/application/check-processing-times.html
Check processing times
Due to the impacts of coronavirus disease (COVID-19), we can’t
- process applications normally
- provide accurate processing times
- Canadians trying to return to Canada
- vulnerable people
- people who perform or support essential services
- check the status of your application online
- make sure your contact information and your application details are up to date
- Use our Web form to tell us of any changes in your application.
- find out about travel restrictions and how to apply