So I have a world where end gateways don't spawn after you kill the dragon. I think I created the world in 1.16. When I killed the dragon for the first time no end gateways appeared. I beat it the second time and again no gateway, so I had to bridge a thousand blocks to get to the outer end islands. Recently I opened the world in 1.17.1 and defeated the Ender dragon the third time, but still no gateways. In other worlds they do generate, so I'm a bit confused why they don't spawn in this world.