In my survival world, after a xp-grind at my endermen-farm, while I was under Bad omen, I left the End and to my surprise the Bad omen effect dissappeared without triggering a raid.
How to reproduce:
Find a stronghold
Go to the end
Kill the enderdragon (and the crystals of course)
do /effect give [playername] minecraft:bad_omen 10000
/gamemode survival
Go through the end portal to activate the credits
I think it is no bug of big importance, but I like to see it fixed. Unconfirmed for other statuseffects/potioneffects.
Duplicate of MC-124177
You actually still have the bad omen effect after leaving the end, but it is not displayed properly.