Sometimes, when I try to get back from the Nether to the portal in my base in the overworld, the game creates a new portal around 100 blocks away from my base. The portal in my base was active as I played in single world.

All new portals that spawned were only a few blocks away from each other.

This did not always happen, when I try to come back from the Nether, but around 1 of 3 tries.