These people continued to question the right of states to certify their own elections after Trump's domestic terrorists invaded the Capitol on 1/6/21. When Congress reconvened after the terrorists left the Capitol (and only about 50 of them were arrested despite the damage and bringing weapons to the Capitol), they continued with their "The election was fraudulent for Biden" mantra. But, by 3:45am on 1/7/21, the votes cast were acknowledged by Congress and Joe Biden's election to the presidency was formally certified.
But it's important to never forget who encouraged "the election was fraudulent for Biden" lie beyond Trump - many Congressional Republicans. Most of them want support by Trump Cultists in the future. Trump Cultists are not going away. But, even though many Republicans voted for Trump, I don't think all Trump voters are Trump cultists. Which means, in a few months or years, these people may see that aligning themselves with Trump may not get them elected. They may claim that they really didn't stand with Trump. These people absolutely engaged in the seditious act of denying the reality of an election. These members of Congress should never be elected to any office in the future by any rational voter: