When you buy using Splitit 'Pay After Delivery' an authorization (hold) is placed on your card for the purchase amount to guarantee payment. This is not a charge.
Only when your order is confirmed as delivered, is payment taken. The hold on your card will then be released.
Whilst the hold is on your card, your available credit is reduced by this amount. When the hold is released, the funds are released back into the available funds on your credit card.
Authorizations show as 'pending' or 'reserved' on your account.