Steps to reproduce:
Make sure "Always Show Toolbar in Full Screen" is disabled from Orion's View menu. Open an Orion window with exactly one tab and the tab bar hidden. Make that window full screen and then open a new tab. The tab bar will then not be hidden and instead appears at the top of the full screen space. The tab bar will hide with the toolbar after mousing over the toolbar and moving away again.
Expected behavior:
It seems more consistent to me that the tab bar should always be hidden if the tool bar is hidden in Full Screen mode, rather than appearing at the top of the screen on new tab open. Safari behaves the same as Orion so it is possible this is not a bug but rather the intended behavior. If that is the case, this can be marked as "No fix".
Orion and macOS:
Orion 0.99.109.1-beta (WebKit 613.1.12)
macOS Version 12.1 (Build 21C52)
Image/Video: