Why do instant Apple Cash transfers not show up in my bank account immediately?

I do instant transfers from my bank account to Apple Cash. It shows I have withdrawn the cash immediately when I look at my checking account. Then hours or days later it has

reshuffled and my bank now doesn’t show all the transactions making me have more money than I actually do. This has been going on for months. These were instant transfers so can’t understand why suddenly they don’t show up when I check online banking. If I look at the Apple transactions under wallet and Apple Pay all the transactions are there

[Re-Titled by Moderator]