Looks like the coating on the crt has been scratched off.

Try something like glass cleaner and see what happens, but avoid methylated spirits or alcohol as that can
remove more coating.

It really annoys me when people don't use their brains when packing stuff, anything that is metal should be
packed in a way that it cannot do any damage to plastic, etc.

When I googled CRT scratches all the results said the same thing -- anything you do will make it worse. They all made reference to polishing removing the anti-glare coating though which I was hoping was something that these 1980s monitors didn't have. I'm surprised these coatings can't be acquired and reapplied/touched up though.

Even if that were possible, You would have to completely remove the CRT to reapply it, preferably after discharging the 25000 volts.

I would still use some glass cleaner though, even LCD screen cleaner if you have it, it shouldn't cause any further probs.