Shadows (Minmazar Boss room) and Shadow Lords (Sandy Crypt) are no longer attacking as they used to instead choosing to use a strength draining attack and standing completely still between uses.
This attack drains strength with no saving throw at an incredibly fast rate.
Further, when strength reaches 0, the character is immediately put to 0hp, again, with no saving throws.
While for most people this is less of an issue, this permanent drain is devastating for RSD's and they can end up being killed in about 6 rounds of combat, or if you had low strength you could be killed almost instantly. by 2-3 shadows.
They actually were always intended to use their shadow touch attack. A long, long, long time ago before the big ai changes, all shadow creatures would spam their touch attacks. Which is supposed to kill the target(efu mercifully just sets you to 0 hp) if they get to -3 strength. They can do it once per round and it's a touch attack, so quite hard to avoid, but improved invisibility helps, but ultimately the only true protection is negative energy protection.
Their attack is actually extremely weak (1 piercing/slashing damage + strength + some minor negative and dc 11 strength drain)and it sounds like whatever was broken with their ai that caused them to use it instead of their 1d6 strength drain touch attack has been fixed. Shadow lords in particular always gave a reasonable chunk of xp for how easy they were to kill, due to how dangerous they are -supposed- to be. Though it's not just supposed to be the shadow lords who do this... but every single shadow, even the small ones. I believe the larger ones drain considerably more strength
While this is yet another horrible experience among many for RSD's. It's one of the many, many, drawbacks of choosing to live a life without magic.
Fairly sure this isn't a bug, as unpleasant as it might have been for you. Though it might be worth suggesting a brew-slot use ability for RSD that gives them Restoration for that rest.
These creatures can be particularly nasty to RSDs, but I can tell you from experience it is very survivable. It's inappropriate for me to give you a list of specific tactics other than to say there are still many magic and psuedo-magical items you can use to avoid/intercept/quickly kill these Shadow Lords as well as possibly remove attribute 'damage'. I had trouble with these until through effort and experience I developed tactics to counter them. Basically you have to reexamine how some items are traditionally used. Some things that are generally detrimental to all other classes can be a boon to an RSD.