The 2020 election's fraud claims were thrown out by courts. They were entirely evidence-free. Even Lindsey Graham gave a concise speech on the night of 1/6 explaining precisely how false those fraud claims were.
The 2016 election involved Russia hacking the DNC and leaking their emails, which became a centerpiece of the election debate ("Hillary's emails!"). It also involved Trump publicly asking for Russia to leak the emails, and then (once elected) firing the head of the FBI and saying in an interview with Lester Holt it was because Comey was investigating any possible ties with Russia.
The response to 2016 was the Mueller investigation. The response to 2020 was an attempted insurrection. One of these is not like the other, and you're attempting to paint a false political logic behind how the two have been treated.
