Since the touchscreen works normally outside Roblox, this appears to be a Roblox-specific touch input issue rather than a hardware problem. Please ensure your Surface Laptop has the latest Windows, Surface firmware, and touchscreen driver updates installed, then reinstall the HID-compliant touch screen driver via Device Manager. If the issue persists across multiple Roblox experiences, it is likely a Roblox client issue.
The best thing you can do is add your experience to the existing bug reports on the Roblox Developer Forum, so it gets more visibility and a higher priority for a fix.