5 to 5.5 years - the same as RHEL "full support" phase.
No it isn't. Ubuntu LTS is supported for 5 years.
https://ubuntu.com/blog/what-is-an-ubuntu-lts-release
>An Ubuntu LTS is a commitment from Canonical to support and maintain a version of Ubuntu for five years.
---
>Not saying it is a bad OS but it is no longer a free Linux operating system with long term support.
Ubuntu LTS is suppored for 5 years, Debian Stable is supported for 5 years, and OpenSUSE Leap is supported 5 years (as far as I can tell - the only documentation I found said "up to" 60 months).
CentOS Stream absolutely provides "long term" support.
>ESM is available through an Ubuntu Advantage for Infrastructure subscription for physical servers, virtual machines, containers and desktops, and is free for personal use.
https://ubuntu.com/security/esm
Note that if you click through "personal use" means "up to 3 machines" and obviously doesn't apply to infrastructure. RHEL has free "personal use" subscriptions too, except they apply to up to 16 machines.
And also:
> Initially, free subscription is available for Ubuntu 14.04 LTS only.