Well for one thing, the court usually had Fridays off. The judge changed it to Wednesday. Orthodox Jews are heavily for Trump. By making court be in session on Fridays and the judge not guaranteeing that court would be done before sundown, the Orthodox Jews could not serve. Another thing, the judge dismissed any potential juror that followed Trump on Truth, but not any juror that followed Biden on Twitter.
I can’t find anything confirming that. It appears from a google search that Merchans courtroom is always closed on Wednesdays because he presides over a special mental health court that day. And during jury selection it was widely discussed that Merchan himself dismissed a woman who posted vitriolic posts about Trump, and that currently on the jury is a man who follows Trump on social media and gets his news from truth social.