MacBook Air 2012 Weird light spots bottom part of screen

I’ve a MacBook air 2012 which got some water spilled over it. Replaced the keyboard and booted without problems, except I noticed this weird marks on the lower part of the screen, just above the bezel. It is most visible on a white background, when logged in for example with the dock present it becomes a lot less visible.

Quick google search and the stage light issue pops up, however in those problems the spots are distributed at regular intervals along the screen which is not the case here.

Pressing on the screen itself does not change the size or intensity of the spots.

Anyone an idea what this could be or how to troubleshoot? Thanks a lot :)

Some additional info about the (history of the) mac below:

Background on the MacBook: laptop is from my mother, so I do not know exactly what happened, but she said the spillage “wasn’t too bad” and at first only some key weren’t working before eventually not responding to any input at all shortly afterwards. (I don’t know if the computer shut down by itself or if it was powered off normally or if simply ran out of battery). When I had the chance to look at it, I opened it up and couldn’t find any obvious indication of water damage and the mac was charging normally, so I figured a keyboard replacement would be a good place to start. So replaced the keyboard and the mac booted without any problems, except the screen issues.

Also, there is a dent in the upper left corner of the body (closest to the charging port, similar to this: https://forums.macrumors.com/attachments... but on the other side), so my guess is it was dropped at some point. The screen issue could therefore be a pre-existing condition unrelated to the water, since my mom doesn’t know if those spots were present before the spillage..