This is similar to (MCPE-84513). The main difference seems to be that the player’s position is ignored, and instead world height or some location above world height is used to determine the illumination for the player.
Steps to reproduce
Be in the overworld.
Make a solid box and fill it with water.
/fill ~-1 ~-1 ~-1 ~9 ~9 ~9 stone hollow /fill ~~~ ~8 ~8 ~8 waterSet time to noon, then set time to midnight.
Go to the End, repeat step (2), and wait a few minutes.
Expected results
Time of day and sky light should not affect underwater illumination in a sealed, opaque box.
Observed results
In the overworld, time of day (i.e. ambient sky light level) determines underwater illumination in a sealed, opaque box. In the End, you experience the End Flash underwater in a sealed, opaque box.
[media][media](Underwater End Flash is at 0:29 in above)
Thank you for your report!
We're tracking this issue in https://report.bugs.mojang.com/servicedesk/customer/portal/2/MCPE-208089 , so this ticket is being resolved and linked as a duplicate.
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