I can confirm that the April patch does not address the screen flashing and green distortion problem.
PROBLEM:
Thus far, all four Pixel 3 devices have consistently flickered like a strobe light and/or the screen would turn green green like an old TV trying to get a signal.
WHEN DOES IT OCCUR (consistent in all devices so far):
---This occurs in an environment that is usually in a low light setting.
---The phone brightness is set between 10 to 80 percent.
---It does in both night light and non night light setting.
---The flashing/green can start at the login screen (but not all the time).
---The flashing/green can start after you've logged in and are using the device.
---This also occurs in safe mode.
---Manufacture reset does not fix the problem.
WHEN SCREEN FLASHING DOES NOT OCCUR (THOUGH NOT SOLUTIONS):
---Generally putting the phones in gray scale and setting brightness to 100 percent has reduced the frequency but is not a solution.
---In bright daylight the flashing rarely happens.
I attached two pictures that show the screen flashing/green after the April update. And another screenshot of the OS.
