Hard mousepad scratches are mostly cosmetic.

Generally, no — micro-scratches from normal use won’t mess up your mouse tracking.

Modern optical sensors are stupidly good at ignoring surface blemishes. They average out tiny imperfections, so a few hairline scratches from your mouse feet or dust are invisible to the sensor. I’ve used an aluminum pad for years that looks like someone dragged a fork across it. Still tracks perfectly.

Plastic pads can get more scratches than aluminum, but same deal. The only time you’ll have problems is if you gouge a deep groove (like you dropped something sharp on it) or if you’re using a really old/cheap sensor that can’t handle any surface variation. Even then, you’d notice it before the mouse stops tracking.

The bigger issue with hard pads is that they wear down your mouse feet, not the pad itself. Replace the skates every 6-12 months.

If your tracking starts skipping, it’s almost certainly the mouse, not the pad. Wipe the lens, clean the pad, or replace the mouse.