I have attended or been involved with five different state universities and a few different community colleges. For computer science, aside from one glaring exception, the default has been some flavor of Linux. The earliest for me at a school was Fedora 7. I think they had been running Solaris in the late 90s; not sure what was before that.
The only glaring exception is Georgia Tech. Because of the spyware you have to install for tests, you have to use Windows. Windows in a VM can be flagged as cheating. I’m naming and shaming Georgia Tech because they push their online courses hard and then require an operating system that isn’t standard for all the other places I’ve been or audited courses.