I'm trying to make a fps game but when I press w + spacebar i go into some noclip mode, is there a way I can disable it?

when i equip the gun (goes into a first person view ) I'm into normal but when I press w to move again, I go into clip mode

maybe a weird glitch or smth?

I know, I should have said about this at the dev forum of roblox but idk how to make a post there