iPhone 11 users are complaining of a new display bug. This new bug does seem to be hardware related as most of the users who have experienced it explains that they get to see it after unlocking their device.
This new display bug appears as a green tint on iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max. And some users seem to experience this after unlocking or turning on night mode.
Nos solution to this problem is available yet and it seems to be a bug with the new iOS 13.5 since users of iPhone 11 series also report experiencing this bug after updating. Assuming it's software-related, Apple will surely fix things up in the coming iOS 13.5.5 which has been made available for developers to test.
As spotted on a comment to a thread on Reedit, here is what an iPhone 11 Pro users have experienced
I can confirm it happened to me a few times on my iPhone 11 Pro already. Always the same pattern - at night in the dark room meaning DND enabled + Brightness level 0. When I unlocked my iPhone the screen was all green but it switched back to normal within ~5sec itself without any action like a restart. I was thinking it's the OLED display thing but now I see it also happens on 11 with LCD so the root cause is somewhere else. Hopefully, it's a software bug.