Capcut – video editing is typically CPU/GPU-intensive, like gaming. It's going to cause your processors to work hard and that means heat.
Your Mac will throttle back the processors if needed to keep the temperatures in a safe range for the computer. That doesn't mean it will be comfortable to use on your lap, Apple calls these notebook computers not laptop computers for a reason.
Even though the M-series MacBook Air models do not have active (fan) cooling, be sure you're using it on a hard surface and not something soft like a blanket, and make sure the openings along the sides are not obstructed (those allow for passive/convection cooling).