That key always exits fullscreen. I do not want that to happen.

Additionally, this behavior seems to override the keyboard shortcuts settings. For example, esc is bound to Stop by default. But if you are loading a page in full screen, esc will exit full screen rather than stop the load.

Also, there are other reports that this behavior interferes with websites that use the esc key.

Therefore, it seems that the behavior of esc is special cased at a low level. So presumably the only way to change this behavior is to file a feature request to the devs.