When a bookmark is created but the dialog is dismissed with the keyboard, you cannot delete the bookmark by re-visiting the dialog again. The icon is simply not present.
Well I lied again and didn’t fix yesterday, but I did fix it today (live on Meta soon)!
Pressing Escape will not save the bookmark @schleifer but I added back in the functionality to save when you press enter inside the focused text box, so if you press f enter it will save a topic bookmark.