The pattern: the left undermines an institution, the right points out that the institution has been undermined, and the left accuses the right of undermining the institution merely by saying it has been undermined.

Example: The latest episode of "Left, Right, and Center", a political podcast that features a leftist, a conservative, and a centrist, plus a guest, who is usually left-wing. One of the topics under discussion was the way in which Trump criticized the judges who shut down his executive order on immigration, despite that it lawfully exercised his constitutional and statutory powers as president. Trump called one judge a "so-called judge" and said that the courts are "political." Naturally, the leftists on the podcast found that this language "erodes public confidence in the institution" and is "insidious" and "dangerous to democracy".

Trump undermined nothing. It was the courts who undermined their own legitimacy by transgressing the limits of their authority. Trump called them out on it.

The judge is a "so-called" judge because he wasn't doing his job properly. The courts are political, and have been for a long time, because they fancy themselves super-legislators. Now, it has become obvious that they want to be super-executives as well.

If the left doesn't want revealed the corrosiveness of their actions for fear that such revelations will undermine the public trust, they should refrain from doing those things in the first place.