Lord is this issue weird.
It’s called “Codename: Chameleon,” and follows a double-agent spy named the Chameleon. He’s stolen some weapon plans that the Shredder wants. The police chase him and he flees in the sewer, only to be caught in a fight between the Turtles and Beebop and Rocksteady.
Beebop and Rocksteady make off with him and the Shredder threatens to mutate him into a real Chameleon unless he tells him where the plans are. The Chameleon does so, but Shredder mutates him anyway… making his strong enough to break free. And turn invisible.
Didn’t think that one through, did you?
Anyway, he returns to the sewer where Beebop, Rocksteady and the Turtles are having a standoff. He intervenes briefly on the Turtles’s side, steals the plans, then burns them so that nobody can get them.
This is a filler issue. And while it’s not horrible, it makes no attempt to hide the fact that it’s a filler issue.