Byobu weird character

That weird character, sometimes displayed as ⌷, is the Ubuntu unicode logo, .

Byobu tries to use Unicode symbols, but sometimes those may not display correctly, if you're on a system that doesn't include that character in its font set. All of Byobu's symbols are tested to display properly on on Ubuntu (with the Ubuntu font) within Gnome-Terminal, but your mileage may vary on other terminals (such as Putty), other Linux systems, Windows or MacOS.

You can disable the logo entirely, by going to the Byobu configuration menu, by either pressing F9 or running byobu-config, selecting, "Toggle Status Notifications", de-selecting "logo", and then pressing "Apply".

And you can toggle all UTF-8 characters on/off by pressing Alt-F5, or running /usr/lib/byobu/include/toggle-utf8.

Full disclosure: I am the author and maintainer of Byobu.