The pursuit of Flynn was spearheaded by people who refused to accept the results of the 2016 election and worked to undermine the peaceful transfer of power, said the White House. These same people are the ones accusing Trump of undermining the election by challenging what appears to be serious voting irregularities in the 2020 presidential election.
That is called "projection."
The White House statement also cites partisans in politics, the media, and the Deep State which sought to prevent Trump from being elected, to prevent him from taking office once elected, and to remove him on false pretenses once in office.
In order to push the false narrative that Trump was somehow elected due to the intervention of Russian President Vladimir Putin, the coup-masters had to make it appear that a high-ranking official was involved in monkey business with the Russians. Flynn was the unlucky victim of their smear machine, accused of "Russia collusion" over an innocent telephone call with the then-Russian Ambassador in Washington during the transition to a Trump Administration.
Yet when Joe Biden's transition people bragged recently that Biden was connecting with foreign officials before inaugurated, the media praised it as a welcome return of the "experts" to foreign policy.
While it is very good news that President Trump is in the mood to pardon those victims of the warmongering Deep State, I very much hope that he is only warming up. It would be a great tragedy if other Deep State victims are left to suffer for their non-crimes.