Is a person considered a braggart or a backbiter if he talks about his kindness to people who did not appreciate him, without confronting them with that?

The action mentioned combines backbiting (gheeba) and reminding (mann), both of which are major sins. Backbiting because he mentions his brother with what he dislikes in his absence, and reminding (mann) because he counts his gifts against him, even if not in his presence, and this is what scholars have considered as reminding (mann). Mulla Ali al-Qari and Ibn al-Malak mentioned that the one who reminds (al-Mannan) is he who mentions what he has given to others, or to show off his own generosity. The one who does this must repent to Allah from both matters.