The vaccinated can still get it, carry it and spread it. So they don't need a mask because why???
You cannot spread Covid-19 if you are not infected. It is not like Typhoid Mary, where you are not infected, yet you are a carrier. The only way to be a carrier, is if you are infected.
If you are fully vaccinated (not half-vaccinated), the odds are low you will get infected. Those who are fully vaccinated and still get infected in that low percentage of cases are typically those who have weak immune systems, such as the elderly. Children and younger adults have a far lower chance of getting infected after vaccination, than elderly adults. If they aren't infected, they aren't spreaders of it.
I think the vaccinated are safe. The unvaccinated however, better get their acts together soon, if they want to survive.