I still remember that they launched GitHub Actions in 2018 and back then I was thinking: They can't even make the website reliable, surely this will only cause them more problems.
https://news.ycombinator.com/item?id=48086786
The earliest recorded downtime for Git Ops I could find is in December 2018. https://www.githubstatus.com/uptime/8l4ygp009s5s?page=32