Same issue on a MacBook Pro 2017 15'', but I've spilled 1 drop of cleaning liquid in the bottom of the screen.
It started hissing. Had a white spot at the bottom of the screen, it disappeared after 12 hours. The 9 shadows however probably won't fix themselves.
Went to Apple and to other 2 repairs, they told me I have to replace the screen. Will cost about $900 USD, either at apple or at other repairs.
I mentioned about the possible cable failure, everyone denied it, said the problem is in the screen, none of them even got to check the actual hardware, they just looked at it.
I think I'll just keep it like this and wait till some other hardware issue pops up.
Ley me know if anyone found a solution.
Update: Right speaker is gone too. The liquid drop was on the left part of the mac.