Yabai Status bar has been deleted. You have to use an external bar instead such as BitBar.
Simple Übersicht widgets as an addition to the Yabai's simple status bar.
Modified version of zenbar.
These widgets function as an addition to the Yabai's status bar.
Add this to your .yabairc file
yabai -m config status_bar on
With Ubersicht installed, run this command
git clone https://github.com/PatrikTrefil/ubersicht-widget-yabai.git $HOME/Library/Application\ Support/Übersicht/widgets/ubersicht-widget-yabai