I thought about that to, unfortunately it did not work
Ok, I posted a screenshot. After removing optifine, I realized there is some red vignette, as if I was on the other side of the world border. I don't take damage in survival though.
No, it's not the same.
Still broken in 1.16.1 Hotfix.
Still broken 4/8/20. I knew of the bug, but I build it anyways for the fish and hoping the bug will soon be fixed.
UPDATE: I have some new information. For context, my overworld border is 255x255 and about 1300 blocks from spawn I discovered that there are 2 borders in the end dimension. The fist one is the main border at 30,000,000 blocks, but it is invisible. You still can't pass it. When trying to move the border in the end, this is the one that gets moved. The other border is where the overworld border is. This one is visible and you can interact with blocks inside it.
By the way, this is not how it works in the nether.
TLDR: On realms, the overworld border is also in the same spot in the end, and it should not.
Let me know if this is a duplicate issue or if I should make a new bug report.