Note that if you have Add bundle items as separate line items to orders? app setting disabled, then this help article is not applicable to you.
If you do have this app setting enabled, then please read below for a solution.
Adding bundle items as separate line items to orders can result in the order’s shipping weight being doubled (as the dummy bundle and bundle items both contain the full bundle weight).
To handle this, please go to Bundle Kit > Settings, find the Bundle Weight section, and enable the Set dummy bundle product weights to zero? app setting.
This would set all your dummy (bundle) product weights to 0 in Shopify, which would help prevent new bundle orders from having their shipping weights doubled.