Systematic reviews of systematic reviews vary greatly in their reporting and methodology as there are no dedicated reporting or methodological guidelines.
Articles that support this problem:
Systematic review finds overlapping reviews were not mentioned in every other overview
2014 : Journal of clinical epidemiology
Risk of bias in overviews of reviews: a scoping review of methodological guidance and four‐item checklist
2017 : Research synthesis methods
Overview authors rarely defined systematic reviews that are included in their overviews
2019 : Journal of clinical epidemiology
Identifying approaches for assessing methodological and reporting quality of systematic reviews: a descriptive study
2017 : Systematic reviews
Systematic review adherence to methodological or reporting quality
2017 : Systematic reviews
Overviews of reviews often have limited rigor: a systematic review
2012 : Journal of clinical epidemiology
A review found heterogeneous approaches and insufficient reporting in overviews on adverse events
2022 : Journal of clinical epidemiology