The Bug

the random end gateway you can find in the outer end island teleports you on the end obsidian spawning platform, the same as the end portals from a stronghold would, but it doesn't regenerates the obsidian platform nor the air layers on top of it.

I suspect that platform regenerate to ensure we have somewhere to land on, so it shouldn't matter where we come from.

Reproduce

go to the end, break some obsidian of the spawning platform, and place some blocks in the 3 air layers above the obsidian, find an end gateway in the middle of the outer island, go through

the obsidian is still missing and the other blocks are not replaced by air

Expected Result

The platform would regenerate after going through an End Gateway