[pmh]

Maybe in the future it will, but it uses Have I Been Pwned. From the FAQ[0]:

How does Firefox Monitor know I was involved in these breaches?

Firefox Monitor gets its data breach information from a publicly searchable source, Have I Been Pwned. If you don’t want your email address to show up in this database, visit the opt-out page.

[0] https://support.mozilla.org/en-US/kb/firefox-monitor-faq#w_h...