After the last update 55.0.3 something strange started happening to the tabs. First of all after sometimes after closing the tab I still see the page. The page disappears only after clicking on another opened page. Secondly, very frequently the tabs become transparent, page title, the X sign disappears and there appears some blank space between the tab row and the address line. Only restarting Firefox helps. For some time. Thirdly, sometimes when opening/restarting Firefox the whole tab row is full of transparent blank tabs with blank pages. Fourthly, the "Options" in the Menu doesn't open. All other icons in the Menu open as usual.

I am on Windows 7.