No idea about federal trials, but where I work, both parties are provided with a list of jurors including their name and their profession or employer. You’re expected to do your own research beyond that.
I understand that one of the federal judges here doesn’t let the attorneys question jurors. He does it himself.
If she disclosed the bias and remained on the jury, it’s a non issue.* If she was asked and did not disclose that’s an issue.
I don’t know about the in-between so this is all my opinion: If she was not asked at all, she and perhaps other jurors should be called back to an evidentiary hearing and the government should have to clear a high bar to show she wasn’t biased during deliberations. I’d also say if she was on twitter *****ing on Trump during the trial, this would be my preferred outcome.
*- I didn’t read the article so I’m basing that on the assumption that what’s been said here was accurate.