My ability to share files to email is not functioning on OS Ventura 13.2.1

Go to Mail > Settings > General. The Default Email Reader should be set to Mail.

Is Mail your default email app? The sharing extension is specifically designed for Mail, not any email client.

I don't know what else might cause it being missing.

If you are using some other email client, dragging the item into the App icon in the Dock should work. Or, the developer needs to create a sharing extension for their app.