That I'm not actually sure on. In the attenuation/dampening section on the wiki, burst streaks are listed as still in need of investigation.
What's also not investigated is how burst damage is calculated when the normal attack damage itself is dampened for passing the threshold (350k for normal attacks). Like whether it's the post-dampened value or the original calculated value that is used as the base for burst damage calculation.
It's something to keep an eye on in future, more debuff friendly events. See what the numbers look like when high powered Siegfrieds are involved :P