Where does a player go when they go through an excess end gateway?
Solution 1:
Each of those gateways links to one of the gateways on the main island, similar to nether portals. If you've killed the ender dragon more than 20 times, new gateways on the main island will not spawn: however, they will still create a gateway on the outer islands. You'll eventually get two or more gateways on outer islands that will link to the same inner gateway.