Why the Su-57 appears on scene, but not the F-35_ _ Top Gun Maverick

Why the Su-57 appears on scene, but not the F-35_ _ Top Gun Maverick

military aviation,military,army,aviation,military aircraft,aircraft,air combat,gcap,6th generation fighter,japan italy and uk fighter,F-X Fighter,BAE Systems Tempest,fighter to surpass the f-35,most powerful fighter in the world,6th generation fighter project,nato fighter,fighter fighter,6th generation aircraft,new 6th generation fighter