Gnome has had vertically stacked workspaces for a long time. The Gnome 40 update unfortunately made the switch to a horizontal layout. A choice that many Gnome users disagree with. This extension completely replaces the new Gnome overview with something that resembles the old style.
Why do you think that https://gitlab.com/justperfection.channel/just-perfection-gnome-shell-desktop is a good alternative to vertical-overview