Facebook – If I send a message request to someone who is not my friend, do they always get notified?

I have searched online for an answer to this question, however, the answers seem to be quite ambiguous.

Basically, if I message request someone who is not my friend on Facebook (but who is friends with some of my friends) will they be notified that I have messaged them?

It seems that Facebook has 2 folders, the main “inbox” and another folder where message requests get deposited, some of which are filtered into a memory hole, never to be seen again (if the Facebook algorithm suspects it is spam) and another “quiet” inbox where message requests that Facebook suspects the recipient might want to read are deposited. However, it is unclear whether the recipient gets any kind of notification, alert or (1) appears on the tab by this folder.

Can anyone confirm their experiences of whether they have been alerted to message requests on Facebook from people who are not their friends?

Thank you.