Help Help with removing thin layer of plastic from bed?

[TruLunaris 0]

While printing with my Ender 3, I noticed that the print seemingly just stopped for no reason. I was printing direct from Cura via USB cable.
When I went to check, I noticed that the layers seemed oddly thin. It seems my bed levelling was not up to snuff and tried to print with the nozzle being way too close to the print bed.
Now I have this really thin layer of plastic or scratches on the surface of my bed (1st Picture). I'm inclined to believe it's plastic since there was a ball of it in the lower-right that seemed attached to the rest of the mark.
I tried my go-to cleaning strategy of using  some isopropyl alcohol on a medical-grade blue cloth (2nd Picture), but that didn't do much to it. I then tried searching my issue, but all I came across were tips on how to remove a completed print from a bed. Stuff like "Use Brute Force or "Run Cold Water Across The Back", that kind of stuff.
Would any of you happen to know how to fix something like this? I don't want a failed print ruining the levelling for all of my future prints.

Extra question, not nearly as important: How do actually keep my bed's level consistent? I've had a few issues of my bed's levelling now. but it's all been problems with my bed seemingly getting lower in between prints up until now.

Thanks in advance for any advice!

[TruLunaris 0]

Also sorry, if this isn't the correct category for something like this. The header said this forum was for "3D Printing Help" so I just kinda assumed.