Ask HN: Why did my spam email count go up by 50x over the last month?

Typically I get one spam email per day in my spam folder and check about once a month for anything that I may have missed. Recently, it's suddenly about fifty spam emails per day.

I can't find my email address in any search engines or in any forums. Have I Been Pwned lists my email in only two breaches from years ago.

What causes something like this?