As of 2021, are there any airlines where masks are optional?

Every flight I’ve taken since April 2020 had mandatory masks onboard and it seems like all airlines actively require them:

  • The FAA continued to mandate masks in the US even when they became optional for vaccinated people
  • New Zealand mandated them on domestic flights even at their lowest public health alert level
  • Western Australia mandates masks on-board even when no COVID outbreaks are present in the state
  • Masks are still mandatory for domestic UK flights even though masking in general is optional in the UK
  • SAS Airlines is very strict on masks even though they’re optional in Sweden

To make it clear what an "airline" is:

  1. They must fly to an airport with an IATA code
  2. They must still be operating scheduled flights as of 2021 (so charter airlines are excluded)
  3. Their tickets must be available for sale to the general public
  4. They must be located in a country which reported at least one COVID case (so small Pacific islands which never had a single case are excluded)