Ubuntu is a fork of unstable Debian packages. You don’t want unstable on your server!
Unstable does not mean crashes all the time. What makes them unstable on Debian is they can change and break API completely. But guess what, Ubuntu freezes the versions for their release and maintains their own security patches, completely mitigating that issue.
There are other reasons you might not want to use Ubuntu on a server but package version stability is not one of them.
Closed source drivers are not really the issue. But competing graphics APIs are. With the move to Wayland open graphics drivers were updated to support the GBM graphics API which if one window manager wants to support then it gains support for all graphics drivers that use that api. But nvidia created its own api, eglstreams that to support required all window managers to write extra code for. Some refused to do that or took a long time to do.which gave shoddy nvidia support.
Some did support nvidia slowly, but then nvidia also switched to support the same api as everyone else (poorly at first but I assume it has improved over the years). Nvidia have also partly released their drivers as open source which has also helped.