What you’re seeing is authorizations, not charges. When you swipe your card, the card # & amount go thru the system, back to your bank who authorizes it based upon the amount of the transaction & the amount of your balance. Many/most authorizations settle a day or two later for the same amount.
For some transactions there will be a difference between the authorization & the final settlement amount. Gas stations & restaurants are notorious for this. They don’t know how much gas you’re getting or the final amount of your bill due to tip when the card is authorized, either when you put it in the pump before getting gas or when they take your card in the back to run it. (Yeah, I know Canada & other countries bring the card reader to your table.)
Some authorizations will never come thru as completed debits, especially travel-related ones. Let’s say you’re planning to go away President’s or Easter weekend. You make your reservations this week for hotel & rental car; they authorize $x today. You may end up cancelling the trip & your reservation for one reason or another; nothing is ever charged to your account. Or you may go on the trip & when you get up to the counter the clerk will say, “Would you like to keep the charge on the card you made your reservation with, a Visa/MC/Discover ending in 1234.” You could say yes or decide that you have a different one that gives you more points/cash back or perhaps free insurance on the rental car so you whip out a different card when you check in. The original card that had the authorization never gets charged anything.
When the bank gets an authorization, they know with fairly reasonable certainty that you’re about to get a charge for that amount; therefore, they lower your available balance by the amount of the pending authorization so that you don’t overdraw your account & leave them holding the bag on a big debit.