Is one considered a liar if they deny committing a sin in the past, such as theft, after having repented from it, out of shame that people might know of their sins?

One who has committed a sin must repent to Allah, restore rights to their owners, and conceal their sin. It is not permissible for them to inform anyone about it, especially after repenting, based on the Prophet’s (peace be upon him) saying: "Whoever commits any of these abominable deeds, let him conceal himself with Allah's concealment." If asked about it, they should not disclose it but rather allude to something else.