Hello,
So you are new to Linux in general and also with the development of Gnome. Yes, the activity overview at log in is a feature added with the new Gnome 40+. To disable it there are a couple of extensions that can do that.
One extension is No overview at start-up - GNOME Shell Extensions
Second extension is Just Perfection - GNOME Shell Extensions also available on AUR
And Dash to Panel can also do that, installed by default on Manjaro, but might not work if you also enable Dash to Dock.