A colleague and I have been discussing this recently, so I'm asking to get 3rd party advice more than I personally could get.
She has been recently promoted to supervisor going from a senior analyst under the same manager to now being a supervisor under that same manager, but she feels that the work she does hasn't actually changed into supervisory-style work and that the only reason she was promoted was to remove the ability for her to earn overtime pay. (Note: jurisdiction here is Ontario, where employees categorized as "Managerial" are unable to unionize and the law doesn't require their overtime to be compensated).
Her workload has increased and she is seen as one of the few people in the company who can honestly collaborate (without back-stabbing or blame-shifting) who can co-ordinate across departments due to her strong intra-corporate networks to get anything done.
She is a very frank, very social person and her direct manager is not. She usually displays strong leadership skills, but is often informal in her conversations especially when talking to other peers in supervisory roles.
She feels that since she became a supervisor, her non-supervisory work hasn't decreased, she's now expected to do more work, without being compensated for it and that often she's being assigned work that a junior employee should be doing instead of her.
In her performance appraisal, her informality when talking to other supervisors was brought up as a negative and something that she needs to work, however, when in reality, her honesty and informality is what creates the strong intra-corporate network she has which makes her such a top performer in the company.
In some cases, she feels that this is a double-standard being applied to her as the male supervisors under the same direct manager are equally as informal, in fact more so at times and that she feels that 1) her direct manager doesn't actually respect her as an individual with a full life outside of work and 2) that the same rules that apply to male peers don't apply to her; instead she is being asked to police her language and her personality when the same policing is not applied to her male peers.
She does not want her personality and communication style to be used against her as discrimination to potentially justify a termination and wants to know how she can protect herself while also re-negotiating the terms of her job so that a) she is no longer being assigned the work of junior and senior analysts, but instead is allocating and delegating such work and b) so that she can achieve some work-life balance by reducing hours worked as she is no longer compensated for the work she does beyond 37.5 hours.