Besides the process of counting illegal ballots argument, it is fraud when you deliberately mislead or misrepresent of the fact such in ballot harvesting techniques, and legal voters suffer a "loss" at these illegal ballots committed by "unknown" voters.

Fraud is hard to adjudicate, but the threshold is lower, so the evidence need not be beyond the reasonable doubt.

I would prefer it is election fraud, not necessarily voter fraud, because it is systematic. These things happened in the past, and everyone was aware of it, but it wasn't as "institutionalized" as this federal election.