Concerns about authorship, credit attribution, and supervisor transparency in group research project + research club

Hi everyone,
I recently graduated with a BSc in Nursing and wanted to get perspective on what is considered normal vs problematic in academic group supervision and credit attribution.
During my final year, I was the team leader of a graduation project with 11 students. I was responsible for most of the core work, including developing the idea, conducting the research, designing and building the prototype, and coordinating the group. Contribution levels varied significantly across members.
When issues of student not contributing arose, my supervisor advised me to document individual contributions and stated that grading would be based on individual performance. He also requested that I be the primary point of contact for all communication. However, in practice, feedback was often vague when I contacted him directly, while another student received more direct and structured responses when they reached out instead.
After completion, the project was awarded first place in a presentation setting. We were later informed that all group members would receive the same grade, despite prior indications of individual assessment. I later learned that other supervisors did assess students individually and all grades were different.

Fast forward after graduation, I continued working with the same supervisor in a nursing research club that we helped establish. My role included contributing to organizing events and developing academic material (including SPSS workshop content, which I primarily developed).
However, I have experienced repeated situations where my contributions were not clearly acknowledged. For example, material I developed for an event was later presented without my name being included in the presentation, and ongoing workshop work is sometimes referred to as collective effort despite uneven contribution.
There is also a pattern of delayed communication, shifting expectations, and unclear attribution of responsibility from the supervising faculty member, which has made it difficult to understand how decisions about credit and recognition are being made.
At this point, I feel extremely frustrated and emotionally drained because I want to maintain a professional relationship for future recommendation letters and academic references but I feel increasingly concerned about lack of transparency and consistent credit attribution.
My questions are:
In academic settings, how common is it for group projects and club-based research work to have unclear or informal credit attribution?
What is the best way to protect your contributions in environments where authorship/credit is not clearly formalized?
How do people typically manage maintaining professional relationships with supervisors they no longer fully trust, especially when recommendation letters are needed?
At what point is it reasonable to step back from such environments without harming future academic prospects?