When entering a Nether Portal with potion effects (i.e. Speed, Strength, Saturation, etc.), all the potion effects are removed after loading new dimension. I haven't tested for End Portals yet, but it probably happens there as well.
How to replicate:
-Go into creative (make sure cheats are on)
-Type "/effect [your player name] 1 1000 10" without quotes
-Build and activate Nether Portal
-Enter to the Nether
Linked issues
Comments
Watching some youtuber guys (mindcrak specifically). The client will see the potion buff disappear but it actually remains. Example being when VinitgageBeef had a potion of invisibility active. After going through a nether portal it showed it was still in affect but to him he was not insibilbe (inventory image or f5). In this case even though he saw himself as not invisible, AnderZEL could not see him becuase the potion status was active.
This bug may actually be just a client side error (still a bug though)
kumasasa
Duplicate of MC-3668
I couldn't replicate this (I don't think) When I entered the Nether, I still had the Speed buff, but my walking speed seemed to be set to normal. Sprinting re-activated the buff's effect.