The bug
The "Bring Home the Beacon" advancement is granted when a player gets near a beacon, even if it was not built by the player, under certain circumstances. This closely relates to MC-117636.
How to reproduce
Create a new creative world, or revoke the advancement by typing
/advancement revoke @s only minecraft:nether/create_beacon.Assure you are not in Spectator mode.
Teleport to the roof of the nether by typing the command
/execute in minecraft:the_nether run tp 0 128 0.Run the following commands:
/fill 3 130 4 1 130 6 iron_block replace/setblock 1 130 13 iron_block/tp 1 131 13/setblock 2 131 5 beacon
Wait for the beacon to activate.
Observed result
You get the advancement even if you did not build or place the beacon.
Expected result
You wouldn't get the advancement, since you did not build or place the beacon.
Can confirm, I just ran into the same issue on a 1.18.2 realm. I attached the video to the issue. It also happens for "Beaconators", not just "Bring home the beacon".
I did not build those beacons, another player did, and it only triggered after I (got kicked for being afk and) relogged.
In case this is relevant, I was standing at 705 -55 -1881, the closest beacon is at 696 -55 -1881, so about 8-9 block away. I was able to reproduce this issue on every relog, as long as I was 8 or less blocks away.