No. Your desktop environment will stay as is.

That’s a flatpak program, so any dependencies it needs are stored in a container which won’t overwrite/affect the rest of your system.

Also, even if not a Flatpak, your system can accept some of the background Gnome/KDE stuff without any problems. Even if you did fully install a Gnome desktop environment, unless it removed the Cinammon Desktop environment, you’d be able to select the Cinnamon one at the login screen.