This definitely is NOT a default Kindle screensaver.
Did you get your Kindle from Waterstones? They are known to "brand" their Kindles with own custom screensavers (which reside in yet another place on the Kindle). Search this forum for "Waterstones screensaver" or similar, there are threads talking about how to get rid of them.
Maybe this helps: https://www.mobileread.com/forums/sho...d.php?t=199050