Yeah, I think it is being reflected through one of the southwest facing windows in One Congress Plaza onto the inside of one of the windows on the northeast facing windows.
If you look at the photo, the reflection isn't just wrapping around 405 Colorado, part of the reflection also appears on the garage area of 405 Colorado - an area of the building that isn't reflective. So it must be coming from inside One Congress Plaza's windows. And you can tell that it's a reflection rather than being photoshopped since 422 on the Lake appears on the left side of the Catherine in the reflection. That blank wall on 422 on the Lake is actually on the right side of the Catherine when looking south.
https://static01.nyt.com/images/2021...y=90&auto=webp