How can God's ability to conceal a person's sins be reconciled with the exposure of that person after a period of concealment?

Concealment is an active attribute of Allah Almighty. He is Modest and Concealing, who loves modesty and concealment. He conceals the sins and faults of His servants in this world and the hereafter. However, Allah may expose some of His servants due to profound wisdom, such as those who seek out the faults of Muslims, or when concealment is a deceptive lure. Exposure may also be a good thing for the servant, serving as expiation for their sins or leading to their repentance.

"As-Sattar" (The Concealer) is not among Allah's Most Beautiful Names.

Exposure may occur from the servant themselves or from others, and whatever happens is by the decree of Allah Almighty.