I'm got a player who has been desperate to know if fall damage is considered blunt damage for the sake of kicking skeletons off of buildings since they are venerable to blunt damage. 

I've been going with fall damage being it's own thing since even were creatures can still be hurt by it but I figured for the sake of clarification I'd get a second opinion or three.  

EDIT: see the answers below for more details when using the 2024 rules.

This was answered in the SAC:

A monster is immune to damage from nonmagical bludgeoning weapons. Does it still take damage from falling?

Yes, that monster is still going to feel the hurt of a fall, because a fall is not a weapon.

Thank you! 

2024 core rule revision a monster with Resistance, Vulnerability or Immunity to Bludgeoning damage would apply when taking Bludgeoning damage from a fall.

I believe no monster in the 2025 Monster Manual have Immunity to Bludgeoning damage, but many have Resistance to it. Since Skeleton have Vulnerability to Bludgeoning damage type, damage of that type is doubled.

Basically, Resistance, Vulnerability and Immunity to Bludgeoning, Slashing or Piercing damage "from nonmagical Attacks" are absent in the core rule revision. For example, a old vs new Will-O’-Wisp 

OLD 

• Resistance: Acid, Cold, Fire, Necrotic, Thunder; Bludgeoning, Piercing, and Slashing From Nonmagical Attacks

NEW 

• Resistance: Acid, Bludgeoning, Cold, Fire, Necrotic, Piercing, Slashing

I agree with you @Plaguescarred

EDIT: I've just added a note in the first reply.

Quote from TarodNet >>

I agree with you @Plaguescarred

EDIT: I've just added a note in the first reply.

 All good my friend! 2014 Skeleton it would also take double damage for same reasons above.