How does "Go Back in Time" work?

How does go back in time work?

I’m curious as Curve mentions you can use the feature to basically have less money block for longer.

How does this work considering I’ve used it before and had both authorizations pending at once before, meaning I was actually £20ish down in usable balance rather than £20ish up.

Granted it wasn’t an issue as I wasn’t using it to gain money back, but because I had used the wrong card.

One use case I can think of is if you offset the balance to a credit card so in effect you get up to 56 days interest free credit.