If you create five or more worlds and then you are in the Singleplayer tab, you will see the information of the lowest world through the bottom bar. But this is only with the information that is in the bottom bar (e.g.: Creative Mode, Version: 20w21a).
This only occurs when Minecraft is in full screen mode (F11) and the screen size is 1920x1080 pixels.
With other screen resolutions, however, this can happen and sometimes all information shines through the bottom bar.