The checkout UI shows free delivery when the user switches the delivery method from normal dispatch to scheduled delivery. The problem only occurs in the delivery box and when the account has the LeanShipping feature configured. although the UI shows free shipping, the purchase total values are correctly displayed and charged.

1. Go to the checkout page by purchasing a random item
2. in the shipping section, select schedule delivery and then select normal dispatch again and the free delivery price will appear on the delivery section

There's no workaround.