Just as no amount of flat temperature data would dissuade the climate cult, so no amount of flat (or even negative!) data on mask effectiveness will shake the faith of the Church of Covid. Beautiful Theories cannot be disproven by mere information.
The "Covid emergency" will never be over. It will mutate and seek out new missions when this particular virus threat abates, repurposing its funding and clinging to its power. They're already talking up the "next pandemic" and how we must forever remain at DEFCON 2 to be ready.
Masks are now a visible and tangible symbol of an entire agenda. Its champions will use every means possible to force you to wear them forever, including corporate pressure, their new favorite tool. Expect commercial mask requirements to linger, especially big corporations.
True believers, meanwhile, will wear their masks with grim determination and scowl ostentatiously at everyone who refuses to join them. It's a new virtue signal that will not go away any time soon. Mask scolding is a quick, easy, heady power rush.
All the while, studies will keep rolling out that masks don't help, and might even hurt. That was fairly common medical knowledge before the pandemic began, but it was aggressively suppressed when masks became a political symbol, and a totem for people desperate to DO SOMETHING.