So, until not so long ago, the coding competitions website of google used to provide your participation history as some certificate of sorts. However the same website now doesn't seem to exist and I really need something as a proof for my rank in one of the past kickstarts. Is there still some way to get that?
Recently found this archive- https://zibada.guru/gcj/
Auto comment: topic has been updated by dumb_boi (previous revision, new revision, compare).
Not an official archive but a lot of competitions with scoreboards (including most recent Kickstarts) are on clist — https://clist.by/resource/codingcompetitions.withgoogle.com/
An official archive by Google: here
There are no round results/participation history/certificates, so I think it's irrelevant for OP's goal.
(Not a certificate but more like a reliable proof of participation and rank)
If you were top 100 in a round, then for most of the rounds, you can find the exact link of the round through a email which kickstart would have sent you which says "Thank you for participating ...". Now grab this link and paste it in the WaybackMachine, it will show you the top 100 standings. But sometimes the page just doesn't load.