Does a broad appeal waiver preclude appellate review of a district court's findings if the judge created a constitutionally impermissible appearance of partiality?

QUESTIONS PRESENTED I. Does a broad appeal waiver included in a plea agreement between a defendant and the United States preclude appellate review of the district court’s findings if the district judge created a constitutionally impermissible appearance of partiality by testifying against the defendant? ii INTERESTED PARTIES There are no