What you're seeing is not a single pane of standard glass but thick, tinted, triple-glazed, composite bullet-resistant glass. You should also know that even standard glass will reflect a small percentage of light, and that the pane of glass itself is a prism especially when thick: combine that with multiple thick composite panes that are spaced in between. That's why the reflection looks so complex, because of multiple and layered reflections.

The most prominent reflection is of the red New Executive Office Building, which is NNW of the Brady Press Briefing Room. I discussed this in a similar thread here, which questioned why there was a view of the red building from inside the Brady Press Briefing room (a smaller but red building called the Peter Parker House, also NNW of the Brady Press Briefing Room).

https://greatawakening.win/p/12hR2wwoht/x/c/4Dx3iRxNLJi

Though you didn't bring it up, you might then wonder why it appears so small in your image compared to this other image in the linked post. The difference in size of the building has to do with the lens' focal length and zoom, which distorts the size of the subjects (note Psaki's small size despite being relatively close to the wall).

Here's a discussion of focal length:

https://photographylife.com/what-is-focal-length-in-photography