None of the big name VPS providers have done this to my knowledge and I make heavy use of nuttcp/iperf3/iftop and lftp multi-threaded rsync-like tool on all my

None of the big name VPS providers have done this to my knowledge and I make heavy use of nuttcp/iperf3/iftop and lftp multi-threaded rsync-like tool on all my instances everywhere. If I use a shared vs dedicated cpu instance I sometimes get short bursts of slowness but I expect that on shared instances and the cause is obvious in vmstat. There was a time and may still be where small AWS accounts had some fixed rate limiting on small EC2 instances but I have no idea if they still do this.