Ex supervisor published last month a photo from my PhD (5 years ago) with other co authors Can anyone of the members of the committee of a PhD thesis use data of the former doctoral student’ PhD thesis without attribution to the PhD thesis?

An ex-supervisor used data at a conference with some co-authors. Unfortunately this data has been already presented in another conference as a poster 6 years ago by myself with different co-authors. This data was derived from my PhD thesis 5 years ago.

When I asked her, she told me that she had the right to. In my PhD thesis, I wrote that I retain the intellectual property rights. However in my PhD program, the university policy is that results from a PhD thesis can be used by both the student and its supervisor.
It's hard to say for sure without knowing all the details and both sides, but typically, whenever an academic paper uses material that's been previously published (and a PhD thesis would count), academic ethics require that it be cited.