Use case:

I am editing a Confluence page using the Rich Text Editor with Firefox on a Mac. I want to use the standard Mac keyboard shortcut to enable bold text, so I hit Command + B.

This launches Firefox's Bookmarks side bar. If I want to enable bold text I have to use the Windows shortcut, Control + B.

This applies to other shortcuts in the editor, like italics etc

We should adopt the behaviour of Gmail which recognises you are in the editor and overrides any browser shortcuts. Hence, when using Gmail on a Mac, pressing Command + B enables bold.