The core problem is the gap between the gross order total a customer paid and the net payout that lands in your bank — and that gap is two things stacked together: fees and timing. Fees are the amount Shopify Payments deducts before it deposits. Timing is the fact that a payout settles a day or more after the sale and usually bundles many orders from a pay period into one deposit.
Walk one order through it. A customer pays the gross total — the product price, any shipping you charged, and the sales tax you collected, less any discount. Shopify Payments then deducts its processing fee. If that order was refunded or disputed, that comes off too. What remains is grouped with every other order settling in the same pay period and sent as a single payout. So the deposit on your bank statement is the gross of a batch of orders, minus fees, minus refunds, arriving after the fact — which is why it can never match a single day's sales figure, and why matching it by eye is hopeless. Reconciliation exists precisely because that arithmetic is invisible from the bank line alone.