In the latest version of the App (26.6.0) it's impossible to close tabs with bar width exceeding titles (which is practically every tab) from the tab bar due the x not appearing.
turns out that they added a (badly rendered) scrollbar to the tab-bar which due to my last tab being a downloaded games tab appeared to be an associated percentage-of-hard-drive-used bar.
While this makes it easier to read the tab names, IMHO it would be better UI-wise to not need to scroll just to close a single tab from the tab-bar
Thanks for the regression report, opened an issue here: https://github.com/itchio/itch/issues/3384
As a separate question: How upset would you be if we removed the tabs mode from the app?