Hi CatLechnar,
Thank you for reaching Microsoft Community.
I'm sorry for the inconvenience this has caused you. Definitely, this is not the experience we want you to have. May I know which Surface Laptop 3 configuration do you have? Is it the Intel or AMD? If it is Intel, please follow these steps below to disable the touchscreen of the device:
Open Device Manager
Expand Human Interface devices
Right-click on Intel Precise Touch
Select Disable device
Close Device Manager and restart your Surface