Yes, that science. The one that looks at available data and reassesses, rather than taking a potentially incorrect stance and sticking with it for no reason other than to save face.
The reassessments haven't been about learning how masks work but about how a particular virus spreads and the efficacy of various types of masks in various settings between parties of varying contagion levels. The advice also has to be grounded in practicality given current circumstances (supply constraints, rate of asymptomatic spread among vaccinated populations, etc)
That’s why “you don’t need a mask” was just a lie to conserve masks for healthcare workers.
Is that following the science?
Many conventional wisdoms we're overturned during these last couple of years. Saving mask for the health care services might have been a reasonable thing to do 20 years ago. But today with Chinese extreme mass production it is entirely feasible in rich states to equip their populations with sofisticated face masks and test for virus infection with anti-gen tests several times every week.
It's a new world.