Hi Nicky,
Have you tried checking Surface diagnostic tool and after going to Device Manager for your keyboard? You can update the driver there. Or you can check if there are any ongoing Windows Updates on your device. You can also check Accessibility Settings, go to Settings > Accessibility > Keyboard, and ensure features like Sticky Keys or Filter Keys are not interfering. Feel free to reach back if any of these didn't work.
Best,
Jeric.