Yep, Unity DE had ads. Then people revolted and Canonical eventually got rid of them and also switched to base Gnome with some extensions.

It definitely happened, I saw it in real time on my install of Ubuntu. But they learned their lesson on this one, I feel.

Not sure why there are some who think this is still a thing, though.

Side note: I’ve not run Ubuntu as my desktop OS I’m quite some time, opting instead for Garuda as of late and have seen no ads thus far :)