More likely it was rival climate channels that want their subscribers so are just going through the vids, finding something that looks copyright and spamming go

More likely it was rival climate channels that want their subscribers so are just going through the vids, finding something that looks copyright and spamming google with the license in hopes the channel is taken down. If you have any kind of popular channel you will experience this as there's money to be made by somebody else gaining all your views.