They were two of the most credible witnesses that I have seen on the hill.

They were also the prototypical whistleblowers, civil servants who tried to raise concerns over special treatment and political interference internally and only came to Congress after all such efforts failed. They were then both allegedly retaliated against by the Biden Administration.

Yet, in its coverage, NBC referred to the men as "so called whistleblowers."

That was not the disparaging description given other such witnesses, including figures in the Trump impeachment.  They were just "whistleblowers" or "respected public servants."