Ubuntu Pro and RHEL are both 10 years for their standard lifecycle, with optional add-ons to go longer. Ubuntu's is called "Legacy Support" to get an extra 2 years, RHEL's is called "Extended Life-cycle Support" to get an extra 3-4 years.
https://ubuntu.com/about/release-cycle#server-desktop-eol-ol...
https://access.redhat.com/support/policy/updates/errata#Life...
I'm guessing it's similar with SUSE and other "business" distros.