When entering or exiting a nether portal there is a chance that instead of being teleported to the corresponding portal in the nether, you will instead be teleported to a seemingly random location. This happened on a bedrock realm. I was the only player online at the time it occurred.

Examples:

I entered a portal at 54, 65, 209 overworld. I come out at -54, 60, 180 in the nether. However, the portal where i should have exited was located at 7, 110, 27.

I entered a portal at 500, 110, 0 nether. I come out at 750, 45, -234 overworld. However, the portal where i should have exited was located at 4000, 65, 0.

This happens both when exiting and leaving the nether. All portals where this happened already had linked portals in the corresponding places in the overworld/nether.