How long for money to be put back in account?

So I tried to make an in-app purchase but I never received the item. Upon speaking with Google support they informed me the payment was cancelled on the app developer end and the money should be returned. Has anyone had experience with this and inform me how much time it’ll take for the money to return to me Monzo acc?

It depends.

If the payment is still pending (scroll down to the very bottom of the transaction) then Monzo will return it to your account after 7 days of them not claiming it

If the payment completed, it’s up to them to give you a refund and Monzo will give you it when they have it.