I noticed when a player travelled from the overworld to the nether, the status effect that they had from a beacon stayed with them and affected the nearby players in the nether.
Host was on Windows 10 - Client was on Android and joined via wifi LAN.
Steps to Reproduce:
Have Player A in the overworld transport to the nether via a beacon near a portal
Have Player B stand near the portal in the nether
Both Player A + B will have the beacon effects for <=16 seconds
This appears fixed as of 1.0.0