Your understanding is wrong.
Voting against result certification is occasionally used as a protest against certain specific irregularities. It is absolutely not common to vote against them, and not in these numbers (i.e. not as a lone congressperson or two drawing attention to something they see as a problem).
[ EDIT: added known historical examples ]
Specific examples: 2016, 11 Democrats rose to object to certifying Trump's results; none of them had obtained a Senator's cosignature and so all were dismissed immediately. Objections were based on reports of Russian interference, subsequently confirmed in the broadest sense by the Mueller and Senate reports, though their findings would not have likely invalidated any actual results.
2004: 1 Senator and 1 Representative raised objections to results favoring Bush from a single state. They both stressed that their objections were not intended to change the outcome of that election.
2001: on the order of 15 Representatives raised objections to the Gore/Bush result, which had been decided by the SCOTUS. No Senator joined them, and Gore himself dropped the Gavel on their protest.