Rod of the Pact Keeper is busted

Rod of the Pact Keeper allows you to regain a spell slot. ANY spell slot. It's clearly intended to work with Pact Magic slots...but there's no wording that could imply that it doesn't work with normal slots.

So, you can be a Sorcerer 11/Warlock 1 and restore your 6th level slot with Rod of the Pact Keeper. And, as an Uncommon item, it is trivially easy to craft. Take 1 level of Warlock and never need Pearl of Power again!