“To avoid paying out lots of money, kernelCTF organizers limit the number of submissions eligible for a bounty.”
Google pays only the first team to submit each kernelCTF window, so a $51,000 bug turned into a race against a four-second proof of work. Timothy Herchen cut it to 0.21 seconds with AVX512 and a server picked for its distance to a Google Form. The submission took 3.6 seconds. Google removed the proof of work two weeks later.