I don't use it, so I don't know the previous behavior. But in Catalina, when I use Ctrl-Up, the desktop zooms out and a narrow strip appears on top, labeled "Desktop 1", "Desktop 2", "Desktop 3", etc. When you move your mouse over to the label, it expands into a preview.
Instead of showing you labels or icons in a task switcher, they just showed you all your windows. Direct representation instead of symbolic proxies.
"Desktop 1/2/3" is meaningless. Show me what's on it so I can see where my windows are. Don't put a dumb gesture between me and what I need to see.
They only did this because of tiny screens, it makes zero sense on any decent monitor.
Old Apple would've put in a hidden pref, tracked its use, and then quietly eaten crow. New Apple thinks they know better than even their power users. It's ridiculously arrogant.