Show Everything is a convenient way to quickly see all files in the folder without actually clearing any filters that may be in place. It’s local to the folder tab it is used in.
You can activate Show Everything mode by clicking the count of hidden items on the status bar. The default status bar displays Everything if Show Everything mode is active.
You can also turn it on using the Folder > Show Everything command on the default Menu toolbar. The Filter Bar has a Show everything checkbox which also lets you toggle the mode on and off.
Show Everything disables all types of filtering within the current folder tab, with one exception: It does not affect folders hidden while in Flat View Mixed (No Folders) mode.