This issue started a couple days ago.
Regardless of zone, when I create a new GCP instance and try to upload to it (via WinSCP), the speed will start around 1 MBps but then drop progressively to 30 KBps or slower. It feels like server-side throttling and I suspect my IP has been flagged for some reason. My connection is fine. Ping to the instance is fine. I can connect via Putty - everything is normal, just the upload speed is being throttled. Download speed from the instance is very high, > 5 MBps.
I haven't been doing anything bad, and my ul/dl traffic isn't extreme. I ran a long-running job a couple days ago that communicated with my client all night, but the total traffic wouldn't have been crazy.
How do I get Google's attention to fix this without having to pay for support?