The intended use is:

params = stats.t.fit(x)
VaR_99 = stats.t.ppf(.99, *params)

We look to the call signature to see what the params are: https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.t.html

ppf(q, df, loc=0, scale=1)

The first param is indeed df, the degrees of freedom.