In sagemath 9.2 the product function have a bug in multiplication.
var('q')
((q^(2/3)+q**(2/5))*(product(1 -q**jt, jt, 1 , 31) * q**(1 /24 ))).expand()
returned a result with leading series to be
...+ 2*q^(121/24) - 2*q^(49/24) - 2*q^(25/24) + 2*q^(1/24)
while
((q^(2/3)+q**(2/5))*(product(1 -q**jt, jt, 1 , 31) * q**(1 /24 )).expand()).expand()
returned a result with leading series to be
...+ q^(653/120) - q^(65/24) - q^(293/120) - q^(41/24) - q^(173/120) + q^(17/24) + q^(53/120)
Notice that both
((q^(2/3)+q**(2/5))*(product(1 -q**jt, jt, 1 , 30) * q**(1 /24 ))).expand()
((q^(2/3)+q**(2/5))*(product(1 -q**jt, jt, 1 , 30) * q**(1 /24 )).expand()).expand()
returned a result with leading series to be (Both wrong in the powers and the coefficients )
...+ q^(653/120) - q^(65/24) - q^(293/120) - q^(41/24) - q^(173/120) + q^(17/24) + q^(53/120)