The combat stat Expertise talks about increasing / decreasing the duration of “debuffs”
Unfortunately this seems like extremely misleading wording because it is actually specifically talking about status effects such as stun/paralyse (a type of debuff) rather than all debuffs.
There are also other locations where debuff is used to talk about a debuff (as we would expect it) such as the Tripod Laggard for Elegian’s touch however it doesn’t seem that this duration is affected by Expertise.
I recommend updating the description of places where “debuff” is used to clarify the type of debuff and be consistent.