Early commentators recount various incidents to explain the antipathy between Dante and Filippo:
Filippo once slapped Dante
Filippo's brother had taken Dante's possessions after Dante's exile from Florence
Filippo's family had opposed Dante's return from exile
Not even just historical characters (for Dante), but also some of his less-favored contemporaries:
https://en.wikipedia.org/wiki/Filippo_Argenti
Early commentators recount various incidents to explain the antipathy between Dante and Filippo: