The bug

An underwater structure generated inside of the end portal, overwriting one of the frame blocks, making it impossible to use. I filled out all of the eyes where possible, but the portal didn't activate.

I've seen something like this happen before - one of the underwater structure type things on a beach generated inside of a desert temple. I understand things like caves intersecting abandoned mineshafts, but some collisions don't make sense or are game-breaking. I mean a quick fix would be to just generate the end portal frame last, giving it implicit priority.

In the picture attached, you can see that I broke the block that actually overwrote part of the frame, because to be honest I was on my personal record speedrun and I was desperately trying to see if I could get it to work, not thinking about bug reports.

How to reproduce

Seed: -5074757443285590333
Coordinates: /execute in minecraft:overworld run tp @s -1271.63 37.00 -998.00 164.70 36.90