The impeachment articles do not limit the case against the former President. To wit:
As has historically been the case. It appears that the entirety of the Political response by the Republican Party is premised on manipulative propaganda aimed at their cult. Republican supporters are promoting describing the charges against the former President as being based on the comments made at the rally in front o the White House on January 6, 2021. This is crafted misinformation for the consumption of the followers that still remain loyal to their treasonous members.
Reading the actual document (click) of Impeachment make it clear that the trial intends to cover All the actions geared towards the insurrection which were acted out over the course of the weeks following the election where the former president lost.