What causes discoloration on MacBook Air screen?

Hi. I wiped my MacBook with a paper towel with water on it to wipe the screen. After i turned it on i noticed a discoloration forming on the bottom left corner of the screen. Then i saw diagonal lines running across the screen. There also seems to be a water, moisture, or condensation under the screen. Can anyone analzye what's the problem. Thanks in advance.

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