⇧⌘V drops the fonts, colours and links a rich source carries.
Text copied from a web page or a document carries fonts, sizes, colours and links with it. ⇧⌘V leaves all of that behind and pastes the words.
Markdown is handled too: a copied Markdown block pastes as prose, without the # and **.
Most apps use ⇧⌘V for their own "Paste and Match Style". Klipto's version takes precedence while it is running, and it does the same job in apps that have no such command. The combination is yours to change in Preferences.
Did this answer it? If not, write to [email protected] and I will fix the page.