For comparison: Windows Server has 5-10 years of support, and MacOS has 3-5.
Upgrading Windows Server editions since 2008 is usually way smoother than upgrading Linux distros because basically everything keeps working more or less the same, often without needing to reconfigure them. Linux world changes things often and breaking compatibility between versions is expected.
In government at least this is a big deal. Will binaries from 15 years ago run on SUSE Linux? Somehow I doubt it.
I've seen hardware utilities that look like pre Windows 95 programs running on modern windows? Is that sound possible?
If it is important enough, the government should demand ownership of the source code, not just take some binary and call it a day.
No glibc will not fix it and the rolling release distros are now patching their libc.
Here is the list of ABI breaking changes:
https://abi-laboratory.pro/?view=timeline&l=glibc
Also a system layer isn't just the C library. Other core Linux libraries often break their ABI too.