Why open weather shell extension is diabled in Gnome Tweak Tool?

This triangle indicates a problem with the extension. So first, remove the version you currently have installed.

Some extensions are available in the software repository of Ubuntu. This is the safest way to install and use extensions, because these have been packaged and tested for your particular Ubuntu version. Install the weather extension using

sudo apt install gnome-shell-extension-weather

or using the Snap store.

Be careful if you install extensions (and any software) outside of the Ubuntu software repositories. Newer versions may not anymore work on your version of Gnome Shell. Make sure to select a version that is compatible with your version of Gnome Shell. You can see your current version of Gnome Shell in Settings - About.