You’re adding forces every time a character touches an anti-gravity brick, and those forces add up to create one massive force.
Edit for clarification: .Touched will fire multiple times as a character walks over the part, which leads to the script adding an indefinite number of forces to said character. It might add one force, it might add a hundred. .Touched on its own is not a reliable way to do something once.
Instead, you should be using a “zone” part to represent your anti-gravity room. Apply the anti-gravity force only when a character has entered the zone, and remove the force once they leave the zone. You can use ZonePlus to detect when a character has entered or left the anti-gravity room, or use your own zone implementation.