Hi! I'm not sure if it's a bad bug, or important, but I want to post it here, just in case.

On 1.17.1, you can make an infinite obsidian "source".

You need a friend. One will stay in the nether portal, and the other friend will break it from the overworld. On my world, my friend was able to spawn near the first portal infinitly and I could break the obsidian anytime. That portal will spawn on, and on, and on, infinitly.

(That random blocks that are broken at the portal in my photo are the blocks I destroyed, just to know)