Here is the best track data for Invest 91C
CP, 91, 2021080700, , BEST, 0, 77N, 1670W, 15, 1012, DB, 0, , 0, 0, 0, 0, 1013, 60, 30, 0, 0, C, 0, , 0, 0, INVEST, ,
CP, 91, 2021080706, , BEST, 0, 78N, 1678W, 20, 1011, DB, 0, , 0, 0, 0, 0, 1013, 60, 40, 0, 0, C, 0, , 0, 0, INVEST, ,
CP, 91, 2021080712, , BEST, 0, 80N, 1684W, 20, 1011, DB, 0, , 0, 0, 0, 0, 1013, 60, 40, 0, 0, C, 0, , 0, 0, INVEST, ,
CP, 91, 2021080718, , BEST, 0, 88N, 1688W, 25, 1011, DB, 0, , 0, 0, 0, 0, 1013, 60, 40, 0, 0, C, 0, , 0, 0, INVEST, S,
CP, 91, 2021080800, , BEST, 0, 95N, 1694W, 25, 1011, DB, 0, , 0, 0, 0, 0, 1013, 60, 40, 0, 0, C, 0, , 0, 0, INVEST, S,
CP, 91, 2021080806, , BEST, 0, 99N, 1705W, 20, 1010, DB, 0, , 0, 0, 0, 0, 1012, 50, 30, 0, 0, C, 0, , 0, 0, INVEST, S,
CP, 91, 2021080812, , BEST, 0, 100N, 1719W, 20, 1011, DB, 0, , 0, 0, 0, 0, 1012, 50, 30, 0, 0, C, 0, , 0, 0, INVEST, S,
CP, 91, 2021080818, , BEST, 0, 105N, 1730W, 20, 1011, DB, 0, , 0, 0, 0, 0, 1012, 50, 30, 0, 0, C, 0, , 0, 0, INVEST, ,
CP, 91, 2021080900, , BEST, 0, 110N, 1740W, 20, 1011, DB, 0, , 0, 0, 0, 0, 1012, 50, 30, 0, 0, C, 0, , 0, 0, INVEST, ,
CP, 91, 2021080906, , BEST, 0, 115N, 1751W, 20, 1011, DB, 0, , 0, 0, 0, 0, 1012, 50, 30, 0, 0, C, 0, , 0, 0, INVEST, S,
CP, 91, 2021080912, , BEST, 0, 117N, 1764W, 20, 1011, DB, 34, NEQ, 0, 0, 0, 0, 1012, 50, 30, 0, 0, C, 0, , 0, 0, INVEST, S,
According to this, Invest 91C never exceeded 25 knots in terms of maximum sustained wind speeds, so it probably would have not received a name regardless of whether it were a tropical cyclone or not. There is also post-season analysis.