All previous runs have been moved to "normal", which is the equivalent difficulty of all pre 2.5.0 runs.

I noticed today most times that are tied for first place in this category use nunu & willump before patch 10.25. These runs should now be put in a spearate category from runs completed afterwards, since this is no longer possible, due to a change to the scuttle crab in update 10.25, documented here, under patch history:

https://leagueoflegends.fandom.com/wiki/Rift_Scuttler_camp

Without the 25% damage increase (which includes true damage from q and smite), Nunu no longer clears the crabs as quickly with that setup. Therefore, all the runs should be invalid in comparison to more recent 10.25 runs, and have their own category.