The hotkeys before this update would allow users to toggle the borderless behaviour on and off. After receiving some feedback it seems that this wasn't really used and people seemed to only handle everything through Favorites / Profiles so the hotkeys have been reworked and they now allow users to quickly add/remove the focused window to/from their favorites.
Just as before this update, these hotkeys can be rebound to something else and can be found in the Settings tab.
I hope you'll enjoy the new update, if you've got any feedback, ideas, requests or issues, join the Discord and help shape the future of ReFrame!