According to their status pages (e.g. https://eu.githubstatus.com/, https://us.githubstatus.com/), their Enterprise Cloud uptime for Actions is significantly higher.
It’s not the same thing as GitHub Enterprise Cloud hosted on the shared global network on github.com.
https://docs.github.com/en/enterprise-cloud@latest/admin/dat...
Edit:
Read that document - why do more people not do the self hosted option with GitHub Enterprise Server ?