Have the following command triggered by a /setblock clock, in the spawn chunks in the Overworld: execute @a[score_timer2_min=200] ~ ~ ~ setblock 5 20 13 minecraft:redstone_block

As expected the command is executed in the End, the dimensions the player was at the moment, right after going through the portal.

However, i did not expect this to go on for another hour, even after having closed minecraft and login back in while still in the End, strongly suggesting to me that the spawn chunks where still loaded, and loaded back up even with no player in the Overworld. However cool i think this is, it does not match previous behaviour of Minecraft.

Had two accounts on, one logged out while it was in the Overworld but moved to the End to see if this was what caused it, but it was not. Spawn was moved to x0 z0 (way before any command blocks were up).

Attachment: the world.