Strict token bucket without fair queuing can cause packetloss bursts for all flows. In my personal experience when dealing with a low(single digit) RTT, I would find that my ex-50Mb connection would accept a 1Gb burst and ACK all of the data. Then the sender would think I had a 1Gb link and keep sending at 1Gb. Around the 200ms mark, there would be a steep slope where all of my traffic would suddenly see ~5% loss for the rest of that second. Once steady state was reached, it was fine. The issue seemed to have a baseline relative to the ratio between the provisioned rate and the burst rate, with a dynamic multiplier not-quite-linearly driven by the link's current utilization. At ~0% average utilization, bursts that lasted longer than the bucket could induce maximum, and not much of an issue past 80%.
I could reliably recreate the issue by loading a high bandwidth video on youtube and jumping around the timeline to unbuffered segments. I had anywhere from 6ms to 12ms latency to youtube CDNs depending on the route and which datacenter. Not only could I measure the issue with icmp at 100 samples per second, but I could reliably see issues in-game with either UDP or TCP based games. Simply shaping to 1-2Mb below my provisioned rate and enabling Codel seemed to alleviate the issue into not-noticing.