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.
Yes, it is the dumbest thing ever, and demonstrates they've forgotten what Exposé was all about and what the innovation was.
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.
Have they fixed mission control's top bar not expanding by default yet? That would be the only reason to upgrade.