Nether portals in overworld won't create new portals in nether in vanilla servers

When creating a new portal in the overworld, this portal will link to an already existing portal in the nether rather than creating a new one, even if they are thousands of blocks away. I've created various servers running with vanilla 1.15.2 and 20w10a and both seem to have the same bug. no matter what.

Example: https://youtu.be/IIr4Pj1D848