I've defeated the dragon and used the created portal to teleport out to the end city islands once. Now I've come back to the end main island from the stronghold portal and want to go to the end city islands again, but the portal now thinks I'm the dragon egg and teleports me to the hole I dug to get the dragon egg after defeating the dragon.

So now I have no way to get to the end city islands anymore, except maybe to fly there with my elytra. Or respawn the dragon to create another portal.

Edit to add: seems there's more broken in the end. See the attached picture. I flew out to the end city islands and found the original portal I used to get back to the main island (see the stairs built up to the lower one). The second portal (the higher one) wasn't there originally.