Pressing tab in the title of a new merge request should take you to the description
Gitlab 13.8.4, Chrome browser
Create a new merge request from a URL. Click in the title textbox (ideally focus would already be here). Press tab. Selection moves to "Start the titel with Draft: or WIP:...". Pressing tab repeatedly then cycles through at least 12 formatting controls before focus is finally in the Description, ready to start typing.
I create dozens of merge requests a day, not having to move the mouse to get into the Description box would be a nice little win.