If you pre-order a D&D product on the D&D Beyond Marketplace or the D&D Store, your card will receive an initial Authorization hold in the amount of the full order price, but will only be charged for the digital items and any physical items on your purchase which are not pre-ordered. Once the physical items you pre-ordered begin shipping to you (usually about a week before the official release so you get it in time), your card will then be charged for those items, plus the shipping fees. Any discounts will be split across the payments based on their portion of the total cost. Tax is applied separately to each transaction.
For example: If you pre-order a Digital/Physical Book bundle for $59.99 ($79.99 with a $20 Bundle Discount), card will initially receive an authorization for for $59.99 + Tax & Shipping. The final charge on the transaction will be applied as $22.49 + Tax for the Digital content ($29.99 - $7.50 Discount). When the physical book starts shipping, you will then receive a separate charge for $37.50 + Tax & Shipping ($59.99 - $12.49 Discount).