[tofof]

Thank you.

Of all the variants proposed in this topic, this is the only one that puts any burden whatsoever on the speaker in the first place (in a good way).

Demonstrating that you've made an actual attempt to understand what your colleague is doing is far more genuine and likely to be received as such. Unlike the mealy-mouthed carefully-phrased examples that just communicate "I care more office politics than actually ensuring this code is high quality," your approach hits a trifecta of signaling respect, actually identifying the concerning behavior of the code, and inviting all the types of productive responses:

You allow the person to graciously admit an error without particularly losing face (they can simply say "nice catch, thank you" and fix it themselves). You provide an inroad to correcting your OWN potentially false assumption -- very helpful, for example, when a junior dev whose work is being reviewed is actually in the right, but politically might be unable to demonstrate that. And your question about the mechanics opens the door to a collaborative discussion in which both sides contribute to the final codebase.