When entering a nether portal from the overworld, you spawn in a different location in the nether that doesn't match with the portal. The video was recorded in a 20w10a server, with a nether hub portal, so It's quite high.

How to reproduce:

1- Place a portal in the overworld

2- Cross the portal

3- Go back to the overworld

4- Cross the portal again, spawning in the nether under the portal, and quite far.

This bug does not always happen, I do not know when it does and when it does not, but I've attached a video and some screenshots.