If water is on any Y level that is not the top of the chunk, it will be visible through an activated end portal, it will also flash rapidly.
Steps to replicate
Put water on a Y level that is NOT the top of a chuck (Y level divisible by 16 minus 1)
Build a portal so the water can be seen through the frame
Activate the portal
Related issues
is duplicated by
Attachments
Comments

[media]