Good question. I think only the application can show this (if coded)
 
	Edit:
 
	https://oukitel.com/blogs/news/widevine-l1-support-what-is-it-how-to-check
 
	I haven't try, but there is google play store application to check it.
 
	An some releases ago, L1 wasn't available on Firefox based browsers, don't  know for now.