Characters
I don't believe this is entirely on the up and up.
— Willow · Buffy the Vampire Slayer
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker voices suspicion that something is not fully honest or above board. 'On the up and up' means legitimate, so the phrase is a mild, understated way of saying the matter seems off. The doubt is stated as a personal belief rather than proven fact, which keeps it cautious.
Context reviewed