Does the presence of individuals like the questioner among attendees of Sharia knowledge lessons, despite the questioner's awareness of the gravity of his sins and his desire for forgiveness even if he were to be punished in the hereafter, invalidate the good deeds of the righteous among them?

Allah Almighty's mercy is vast, and He accepts repentance from any sin, be it disbelief or otherwise, as evidenced by the verses: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" (Quran 39:53), and "But indeed, I am the All-Forgiving to whoever repents, believes, and does righteousness, and then is guided." (Quran 20:82), and "Except for those who repent, believe and do righteous work. For them Allah will change their evil deeds into good ones." (Quran 25:70). The good deeds of the righteous are not nullified by the presence of sinners among them, for everyone is held accountable for their own deeds, and no soul will bear the burden of another, as Allah Almighty says: "Every person is a pledge for what he has earned" (Quran 52:21), and "And no bearer of burdens will bear the burden of another." (Quran 35:18).