Once entering the End Dimension, the structure located in the middle doesn't generate, although the End Towers look modified, but since the middle structure doesn't exist, they never get to blow up. Instead, the Dragon spawns without the summoning animation, with no crystals to heal him, and once killed, no exit portal appears. Also no Endermen seem to spawn in the island.

The modpack is on 1.18.2 with 170ish mods, but no other mods appear to modify the End Island.

make a modpack with only this mod and test.