There are many tools available to critique qualitative research. For instance, you can use JBI's tool for critical appraisal. Here are some of the tools.
Schou, L., Høstrup, H., Lyngsø, E.E., Larsen, S., Poulsen, I., (2012). Validation of a new assessment tool for qualitative research articles. Journal of Advanced Nursing, 68 (9), 2086–2094. doi:10.1111/j.1365-2648.2011.05898.x.
Kmet, L.M., Lee, R.C., Cook, L.S. (2004). Standard quality assessment criteria for evaluating primary research papers from a variety of fields. Retrieved from: https://www.ihe.ca/advanced-search/standard-quality-assessment-criteria-for-evaluating-primary-research-papers-from-a-variety-of-fields