9/10 times when I am coming back from the Nether through the portal at my nether hub, a new portal is created about 500 blocks away from the one in my base. This has only happened in 1.16.3. I break the newly created portals every time I exit the Nether and find myself on the other side of one, but the issue won't resolve itself. I suspect that either the coordinates in the Nether or Overworld have been messed up or it has something to do with the new portal I made in the Stronghold I found NW of the portal, but the new portals spawn SW. Very weird bug.