Mentioning somebody in public snippet's comment does not send them a notification

Summary

If I make a personal but public snippet and then create a comment, mentioning an user, that user does not get a notification.

Steps to reproduce

• Create a public personal snippet.
• Create a comment with @user in it on that snippet.

Example Project

https://gitlab.com/snippets/1882832

What is the current bug behavior?

User does not get any notification.

What is the expected correct behavior?

User gets a notification (preferred). Or mentioning should not be possible.