Did you actually receive a decision letter from IRCC stating your decision was reversed and your application has been approved or are you just assuming that because the status on your IRCC account reverted to “in progress”?

The decision letter you have from IRCC stands until they replace it with a new decision letter. If your application status changed from “closed” to “in progress” in your IRCC account that is not an indication that IRCC reversed their decision on your application. It could be any number of things including your account being updated with information that came in after you received your refusal letter, a glitch in the software or maybe they just have not changed your application status to “closed” and you just assumed the “in progress” is a new status.

Until you receive a letter clearly telling you your application decision had been reversed, your application decision has not been reversed.