Been farming felwithe for a hot minute prior, I can tell you that the vendors agro through walls and doors there,@ swish hey you tried farming there since agro range change? Pretty sure they didnt agro through walls run outside of their homes and through doors to kill you before but if you tested it I am welcome to input.

Please make sure you test it though, seen multiple peeps who have not slayn guards since patch and have not taken a look.

It aint classic, for either the felwithe or kelethin guard hunting. Used to whack those on Brell Serilis with a 52 mage of all classes, and single pulling and killing was what nearly all of them were. The Felwithe guards absolutely did not lay on hands or cast spells other than a low level heal, unless I used an earth pet and rooted one at which point a LoH could trigger at a certain health threashold.

I gave P1999 the nod for giving mobs actual spells and abilities they should have even if it's wasn't classic, because it's just good for the game. The merchant aggro is 100% off though.

devs don't care about bugs unless it's a benefit to the players, if it hurts players it doesn't matter

Can also confirm this wasn't the case during live classic. My first character was a Gnome Necromancer and I leveled up a LOT on guards. Misty, RV, HK, Kelethin, Neriak, Ogguk, Grobb, Felwithe, Kaladim, Freeport... never do I remember vendors agroing while pulling guards.