If you time out when going through a nether portal, it doesn't complete the process to get you to the portal in the nether and when you log back in you are in a random location, which sadly due to being in the nether is often lava.
this can also happen when going through an end portal ans the same thing goes; time out and when you log back in you are at a random location in the end which 9/10 times is floating falling down into the void with all you hard earned items !

I have witnessed this bug happening to a youtuber by the name of xisumavoid (happened on a livestream uploaded to his second channel xisumatwo) and ive had it happen twice to myself

I would have thought you should have gone straight to the other side

Instead when i went through and timed out, i was still at the random location in the nether.

To reproduce you will need to time out when going through a nether portal on your way to the nether. Because you cant disconnect when travelling between worlds you will need to have bad internet (like i).
When you time out, log back in and you will find that you aren't in the location you should be in (e.g beside the nether portal) but in a completely random location which could be inside a wall or lava making it deadly for survival players (like i).