So, just to point out - the person is talking about badmouthing, you are talking about whistleblowing.
These are not the same thing at all.
In the US, talking about improving working conditions is also protected, but it's also not whistleblowing, either.
As a lawyer, i can tell you a lot of people badly misunderstand what "protected concerted activity" covers. It is not about your individual complaints. Explicitly not.
See, e.g., https://www.employerlaborrelations.com/2019/04/30/nlrb-publi...
"Charging Party 2 posted a 23-minute live video on Facebook during work hours and while in uniform talking about the discipline for wearing improper shoes and the confidentiality provision in the disciplinary notice, referencing the wage-and-hour lawsuits, making crude and disparaging jokes and comments about a supervisor, and stating that by asking Charging Party 2 to sign something interfering with free speech, the conduct of the company’s officials was “against the United States Constitution and you need to be shot on sight.”
As far as i can discern, hacker news would consider this protected because it complains, somewhere, about their working condition, and was in fact done as a direct response to being disciplined.
However, NLRB says
"The Division of Advice found that although Charging Party 2 referred to subjects in the video that could have been relevant to employees’ mutual aid or protection, the comments were entirely individual complaints and there was no indication that Charging Party 2 was speaking for other employees or seeking to act in concert with others.
...
"
(They found it okay to fire this person)
In fact, the company had filed defamation lawsuits against the charging parties over the facebook videos, and the NLRB found that was okay too, because they weren't for protected activity.