A timely reminder of the definition of authoritarianism may help remind you why mask mandates are authoritarian. It's not the most authoritarian thing in the world, but trying to argue it isn't authoritarian is to deny the obvious.
"favouring or enforcing strict obedience to authority at the expense of personal freedom"
The state mandates all sorts of restrictions on personal freedom for reasons of public health and safety.
I'm not allowed to burn certain types of fuel to heat my home
I have to wear a seat belt when driving
I'm not allowed to smoke in the pub
I'm not allowed to ride my bicycle on a motorway
I'm not allowed to drive without insurance and a driving licence
These mandates fit your definition of authoritarianism. In which case 'authoritarianism' is not a particularly useful term. How do you distinguish between the state imposing restrictions on personal freedom which are acceptable and sensible, and those which are not? Presumably there needs to be some sense that the restrictions are proportionate. In which case we're into a discussion about how bad Covid is and whether masks are a useful measure. I suspect that's what drives people's differing views on mask wearing.