If you summon a Dragon in the Overworld and kill them there by a Diamondsword, it will spawn a Portal to "Sky", not to "The End". In this world, you can't find anything, there is nothing. On the Portal, where is made by Dragon, you can't see the block "end_portal". The texture is missing and you can see the next block under them. And the Torches is showing to the Bedrock, not outside.