It does not match my observations. As a trivial example - code in Unable to create initial ram filesystem, cannot boot - #34 by 40476
It is entered as preformatted text without explicit format indication ( forums.opensuse.org/raw/179392/34), so should be auto-detected. When I paste the same lines on this demo site, it is detected as XQUERY and highlightend. But not on the forum:
And yes, auto-detection is wrong in this case, but that is not the point 