Setting aside the fact that headless chrome or other browser testbeds do a good job at hiding their presence, what could be the vector for a botnet infection if this were true? Extensions?
It doesn't look like headless chrome, or headed chrome, or any kind of chrome... because there's just requests for one file and no other resources. Chrome would do a lot of other stuff.
This is a wget loop or some other minimal agent with a changed user agent string.
Could even be just a user with a few beefy machines and a lot of proxies.