בעל תשובה – אל יאמר לו זכור מעשיך הראשונים
The Mishna in Bava Metzia 58B says that we’re not allowed to tell a person who repented to remember his earlier deeds. It does not say not to mention their transgressions; it says not to mention any of their deeds.
A person who does teshuva constantly should not be reminded of any of their earlier deeds, even Torah and Mitzvos. Because such a person always improves their service of Hashem, so they’re embarrassed by even their earlier good deeds.