The vast majority of health experts agree that mask use is effective in limiting infections from C-19 & the resulting ill health, long term negative health effects, hospitalizations, ICU patients, loss of work, and deaths.
If they thought masks didn't work, are useless & the virus is not at all hindered by masks, then we would be probably seeing more lockdowns around the world.
As it stands masks are mandated or recommended by the vast majority of nations on the globe.
The scientific evidence says they work and are effective against the pandemic. See the threads on the subject for more info.