Lead by Example, Not by Lecturing
andreacanton.dev
andreacanton.dev
It is also very frustrating to watch people get promoted after taking or assuming credit for all the work you quietly do behind the scenes.
About other people get promoted by the work you do quietly, I think there are three factors that makes a work not noticeable:
1. the quality of the work 2. the presentation of the work (show your work to people that maters) 3. the direct manager unfairness
The first two are in your control, if you think you have done all you can do. I think you should act to change the situation: talking to HR about the situation and/or search for another company