There is no clear evidence at all, just suspicions which I'm more than happy to entertain. It would be foolish to fall for the "lack of evidence is evidence of abstinence" trap.
I was actually rooting for Trump to find election fraud, it would only bolster the US belief in democracy and democracy as a whole. If Trump was cheated, who else was cheated, it would be interesting to put every election for the past 20-30 years under scrutiny.