Windows 10 spotlight image files location

%userprofile%\AppData\Local\Packages\Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy\LocalState\Assets

https://www.howtogeek.com/247643/how-to-save-windows-10s-lock-screen-spotlight-images-to-your-hard-drive/

Search Linux Kernel to find out when a feature was added

Use the LKDDB (Linux Kernel Driver DataBase):

https://cateee.net/lkddb/web-lkddb/IP_SET_HASH_IPMAC.html

Search a CONFIG_xxx and it will tell you since what version of Linux kernel it was added.