Back in 2009, we would have noticed a 40ms swing immediately. The old SmokePing graphs on CRT monitors, they don't make them like that anymore. You felt the network.
My HostHatch VPS in Amsterdam was hitting Hetzner in Falkenstein at 78ms. Should be 12. Should be. I started tracing.
Turned out HostHatch's upstream was routing me through Chicago. Yes. Illinois. For a 400km path. Their cost-optimized L3 blend had a "temporary" path preference that lasted three months.
I have screenshots. MTRs. BGP looking glass outputs — https://bgp.tools. Back in 2009, we would have called every NOC until 3 AM. I am older now. But I still have the screenshots.