How in Avernus did I totally miss this secret treasure-stuffed shortcut to the Underdark in Act 1 of Baldur's Gate 3 no less than seven times?

pcgamer.com:

I've played Baldur's Gate 3 a lot now. And, let me tell you, I've played through Act 1 more times than a lot. I just can't help creating new characters! This restart-itus has become even worse recently, too, thanks to me delving into the world of Baldur's Gate 3 cosmetic mods, which are letting me take character aesthetics to a whole new level.

And, while I'm now overly familiar with Act 1 of Baldur's Gate 3, I'm still astonished that after playing through the game so many times, with so many different characters, I'm still being surprised by in-game content that I've never seen before, such as my recent discovery of a swag-laden shortcut into the Underdark that I'd totally missed on every other run to date. Naturally, spoilers now follow.

I'm referring to the Zhentarim (Faerûn's black market trading organisation) hideout, which while I'm sure some PC gamers have found during their playthroughs of Baldur's Gate 3, I managed to miss entirely, on repeat. Well, entirely until I ran through Waukeen's Rest with my most recent character, the wood elf druid Flidais, and noticed I'd never been in that particular locked door in the inn's stable area.

The door in question can be bypassed in a number of ways, be that picking its lock (Astarion FTW!), breaking it down or, if you get a bit stack happy with crates, having one or more of your adventurers jump onto the roof of the building and then sneak in to it around the back through a whole in the rear wall. Equally, if you have any characters with Enhanced Leap or Misty Step, or a Potion of Flying on hand, then you can also get up on the roof tiles that way.

Regardless of the option you choose, proceed past the door and then avoid being ambushed by a crouched, ambushing Zhentarim