I had this issue on one of my personal sites. It was a blog I used to write maybe 7-8 years ago. All of a sudden, I see insane traffic spikes in analytics. I thought some article went viral, but realized it was too robotic to be true. And so I narrowed it down to some developer trying to test their bot/crawler on my site. I tried asking nicely, several times, over several months.

I was so pissed off that I setup a redirect rule for it to send them over to random porn sites. That actually stopped it.