Nether portals TP to wrong location

After the 1.13 update bringing foxes, one member in my realm repeatedly had issues with Nether portals that have been around for over a year. He would enter the nether through a new portal but would exit through an old portal and it would place him in the overworld in the wrong location. It seems to be somewhat random, but the portal he exited through would be 1-3 maps away from where he sould be.