Dedicated proxies being throttled down

Hi
I have a package of 10 dedicated proxies running on my scraper.
Used to run at 50-80 threads.
Now running at only 1 or 2
I'm trying to track down what is happening. Could this be my ISP or could it be google somehow tracking me and slowing me down?
Ideas needed.
thanks
P.S. I tried switching on my VPN but makes no difference.

Maybe your proxies IPs are blacklisted...

throttled on the proxie end maybe , or it might your end