The AC Valhalla drunk after loading bug is a new addition, arriving in the game as part of its holiday celebration, Yule Festival. Assassin's Creed games have a history toward the buggy, but the festival, which began Dec. 17 and runs until Jan. 7, appears to have upped the bug quotient even as it gives players the chance to complete special quests, activities, and competitions.
AC Valhalla Drunk After Loading: How to Fix the Bug
One such competition, the Yule Festival drinking contest, appears to be the source of the drunk after loading bug. After players compete in the drinking contest, they become drunk in-game every time they load into the game, respawn or wake up. The effect doesn't dissipate over time, making it rather difficult to play the part of a stealthy master assassin while stumbling around.
Players have found that fast traveling can fix this bug. Other possible fixes include restarting the game entirely or restarting the console itself.