Biased because there’s no opportunity for any formal pushback or debate, calling of witnesses that would be favorable to Trump, they can suppress anything that doesn’t support their case, etc. Even though there are two republicans on the committee, they clearly do not like Trump.
That’s not to say their findings cannot be legitimate, meaningful, or relevant. This is akin to having a trial except you’re not allowed to put up a defense and the prosecutor can choose which evidence to suppress. Sure, this committee isn’t a trial, but in effect it is intended to be the court of public opinion, which is why they went to such great lengths in producing the televised presentations. I’m not sure how you would argue how a committee investigation like Jan 6th is not biased. It is by the nature of what it is.
Polling suggests that the Jan 6th hearings only swayed like 1% of people. Most people had their minds made up already. And those who somehow believe Trump was innocent of any wrongdoing already see the committee another partisan “witch hunt”.
Don’t get me wrong, I think Trump should have been impeached 100% over January 6th. It would have saved the country a ton of time, money, energy, and drama. Better yet he should have resigned himself if he had any shred of dignity.