“Penance” is still absent from the text.
Jesus said “forgive” He did not give instructions on what a repentant sinner is supposed to ‘do’ for church leaders to gain forgiveness.
Meting out penance is not seen in the NT. We do see rebuking, reproving and correcting a brother for sin to lead them to repent; we see church leaders remove the unrepentant from fellowship with the hope of restoration.
We also see the promise of a loving Heavenly Father who will chastise His children.
Purgatory by chance????