Not sure what the issue is, or what is causing it. But every nether portal I have ever made has been a bit janky. When I make a nether portal instead of it creating a new portal in the nether based on the nether world math. It ties in to a portal that already exists. So this means not only does my portal not take me to the proper location (relative to the over world where the portal was made). But when i try to go back through the portal into the Over world, I come out somewhere else, most of the time halfway across the world. Out of the 4 portal I have made 3 of them linked to Nefyoni/Asdailed portal in their house. The other one linked to a field. This is very annoying, normally as I player i wouldn’t really care I would just use /home and /spawn as needed. However I made a portal for my city for gathering resources and it comes out in Nefyoni/Asdailed’s nether house, and goes back at their over world house. I’m sure no one wants people in the city passing through their land every time they need to go into the nether.
It’s not going to be addressed because it technically isn’t a problem, but a design consequence. When you create an overworld portal, it searches for a location to put it in the nether. This may be dozens of blocks away from the proper x,z position. (it may even find an existing portal within range and use that) But that means when you go back through it, and it searches for the nearest portal on the other side, it’s dozens x 8. This can leave you 100s of meters away from where you went in. The only way to “address” this would be to have the portal generator embed them into solid walls.