Ubuntu is notoriously finicky as a server. multiple issues with how system configuration is different from other servers like Debian, redhat, etc. firewall used to be an absolute terror. also, as described, your patch levels are tailored to the whims of a corporate entity that historically has sided with desktop stability and experience over server stability and performance.

while we're at it, canonical captures and sells system information like Microsoft does. by using Ubuntu, you become the product. IDK how much you know about companies that sell their consumers data, but typically they put profits over security.

I've worked for a handful of MSP/CSP vendors over the years and they only offer Ubuntu as a server option with one big caveat. you are responsible for the maintenance of the system. lo and behold, four years later they always come crying about how they're about to fail an audit because it's never been updated, or is misconfigured, or was hacked because they installed a bad library, ad nauseam.

from my own experience using it, though aged, it came with a service that was listening on port 3306. was it mysql? nope. what was it? dunno. I killed everything on that system that wasn't required by the kernel. still listening. couldn't install a database on it, so it was wiped and I never used it again.

simply put, Ubuntu is a desktop first OS. if you use it as a server you're going to have a bad time because statistically speaking only amateurs use it that way.