I came across this website that has two URLs..a desktop and a mobile version.
https:// www.myglamm. com /buy/skincare/moisturiser https: //m.myglamm. com /buy/skincare/moisturiser
The canonical for each of them is the desktop URL. But if you search for the desktop one with a site: it shows up that the page is not indexed whereas if you search for the keyword myglam skincare moisturiser the desktop URL shows up on the SERP.
site:https:// www.myglamm. com/buy/skincare/moisturiser
Also if you check the cache for the desktop URL it shows the cached version of the mobile URL. What could be the reason?