I did some comparing current spelldata to spelldata from dragonflight. Permeating chill was two spellids before, one for the talent, and one as a baseline passive that applied to only disintegrate. The talent was removed, and the baseline passive was altered slightly.
Name : Permeating Chill (id=381773) [Spell Family (224), Passive, Hidden]
Effects :
#1 (id=1012819) : Apply Aura (6) | Proc Trigger Spell (42): Permeating Chill
Base Value: 0 | Scaled Value: 0 | PvP Coefficient: 1.00000 | Trigger Spell: 370898 | Target: Self (1)
Description : Disintegrate reduces the target's movement speed by $370898s1% for $370898d.
Name : Permeating Chill (id=381773) [Spell Family (224), Passive, Hidden]
Effects :
#1 (id=1012819) : Apply Aura (6) | Proc Trigger Spell (42): Permeating Chill
Base Value: 0 | Scaled Value: 0 | Trigger Spell: 370898 | Target: Self (1)
Description : Your damaging Blue spells reduce the target's movement speed by $370898s1% for $370898d.
The first is the original from dragonflight, while the second is how it is currently. I cut out a bunch of the middle stuff that is basically the same from one to the other. The description was the only real thing that changed, which says it should be working with all spells. It only working with disintegrate reveals it is bugged and not intentional.
We can verify that the simc spell data is correct via the api, using /dump to grab the returns of C_Spell.GetSpellInfo(), IsPlayerSpell(), and C_Spell.GetSpellDescription().
[09:37:22] Dump: value=C_Spell.GetSpellInfo(381773)
[09:37:22] [1]={
[09:37:22] castTime=0,
[09:37:22] name="Permeating Chill",
[09:37:22] minRange=0,
[09:37:22] originalIconID=135838,
[09:37:22] iconID=135838,
[09:37:22] maxRange=0,
[09:37:22] spellID=381773
[09:37:22] }
[09:37:27] Dump: value=IsPlayerSpell(381773)
[09:37:27] [1]=true
[09:53:34] Dump: value=C_Spell.GetSpellDescription(381773)
[09:53:34] [1]="Your damaging Blue spells reduce the target's movement speed by 50% for 3 sec."
