Thanks Jonathon for your idea, however I forgot that my address bar is a non-default location, which causes it to not be displayed when moving the mouse up. Only the tabs are displayed in my case.
Just using the Customize option under View, I moved the address bar to the top bar (with File/Edit/View etc.), and hid the Navigation and Bookmarks toolbar, to make more room when not in fullscreen as well.
So while this doesn't allow me to use Jonathan's workaround, I don't think it is the cause of the issue since he confirmed it doesn't gain focus on a new tab in fullscreen in the normal position as well.
Thanks Jonathon for your idea, however I forgot that my address bar is a non-default location, which causes it to not be displayed when moving the mouse up. Only the tabs are displayed in my case.
Just using the Customize option under View, I moved the address bar to the top bar (with File/Edit/View etc.), and hid the Navigation and Bookmarks toolbar, to make more room when not in fullscreen as well.
So while this doesn't allow me to use Jonathan's workaround, I don't think it is the cause of the issue since he confirmed it doesn't gain focus on a new tab in fullscreen in the normal position as well.