Nether portal mechanics not updated to Java's 1.16 changes

The bug

In 1.16.2, Java Edition updated portal mechanics with two major new features:

• The search radius is now proportional to the dimension scale factor, meaning portals will only search a range of 16 blocks in the nether, compared to 128 in the overworld
• Portals use the POI system to cache links, meaning two portals that are linked will stay linked until one of the portals is destroyed

These changes were not ported to Bedrock Edition, meaning the confusing behavior described in MCPE-39609 still persists.

More information about this change can be found in MC-197538