Arcane restoration and Warlocks

In the new 5.5 Villainous Options, the Path of the Lich feat "Arcane Restoration" allows you recover up to 4 combined levels of spells slots when you use Soul Syphon.

My question is: How are the warlock pact slots used then? If I am a level 9+ Warlock, my pact slots are treated as 5th level. Does that mean I don't regain any pact slots once I reach 9th level?

Quote from Tynium >>

In the new 5.5 Villainous Options, the Path of the Lich feat "Arcane Restoration" allows you recover up to 4 combined levels of spells slots when you use Soul Syphon.

My question is: How are the warlock pact slots used then? If I am a level 9+ Warlock, my pact slots are treated as 5th level. Does that mean I don't regain any pact slots once I reach 9th level?

That's correct. The magic item Pearl of Power has a similar issue where it stops being useful for Warlocks past a certain level.

These things just aren't really intended to be used by Warlocks.

While I might agree about a magical items not having a description that fits pact magic, this is a feat for a very new Path of Villainy in which the specify that pact magic users can use it.  This truly seems like an oversight, but I am unsure what the remedy would be other than upping the total recovery levels to 5 instead of 4.  Or just outright saying up to four leveled spell slots or 1 pact magic slot.

Thanks for your reply :)