I host an old blog on netlify. I don't update it anymore, but a few months ago I started seeing a large uptick in subscribers. They were all subscribing through the netlify subscription form. It was around 8 to 10 new subscribers a day where before it was one every couple months. I emailed several of the new subscribers and got no response. After a few days I strongly suspected these were not real subscribers.

But why would someone waste their time adding a few subscribers to my old, non updated blog everyday? A couple weeks later I got an email from Netlify saying that I was being upgraded to a payment plan because of the amount of activity on my Netlify hosted form.