We have a scene where our input reflect bad reflection on a reflective surface.
Keyer on(weird reflection cutoff the reflection of TV):
Keyer off(reflection looks normal):
The scene is using Plannar reflection, and the option of "Mirror offset" does nothing at all.
Are you sure you’re actually using planar reflections and not raytraced or screen space reflections? To be sure, turn off raytraced and screen space reflections completely.