Whataboutism is when you bring up something about person A, then the only argument against it is something relating to person B.

For example, when you point out the call the president made to the secretary of state in Georgia begging him to "find" 11,780 votes. Then, without a great excuse, the other person brings up Biden's mental decline.

Both true, both concerning, but the reply just being blatant and desperate misdirection.