I'm using Lenovo tb3 850f and I noticed this problem when I was trying to defeat the Ender Dragon in creative so I know what to expect exactly when I'll actually do it in my survival world but I noticed that when I enter the portal and spawn on the obsidian platform and go to the main island,the end gateway portal's spawn animation can be seen(the purple beacon beam)...taking a closer look I saw that the exit portal is also generated already,( without the egg btw) but everything else is like how it's supposed to be...end crystals,iron cages, everything is normal besides the portals.

This bug potentially can be used to leave the End without dying while the dragon still lives,and to go to the outer islands get endgame stuff without a need to kill the final boss of the game.

I could attach screenshots but one can say that they are fake so i don't feel like doing it,but I can if that can help or something.