[Question] Base rate of RCT from developing countries finding unexpected effects

The last few months I have been stumbling onto RCTs conducted in developing countries, with great results in treating Covid-19. The evaluated treatments seem apriori unlikely to generate these great results, e.g. this gargling study from Bangladesh, or this honey+black cumin seeds study from Pakistan, or Bromhexine from Iran all have results that would revolutionary-if-true. FWIW, and on the face of it, none of them can be described as garbage (decent sample size, randomized, p- preregistered for the Pakistani study, etc.)

This question however is not about these particular studies, but which base rate I should be using to evaluate such studies. I am coming up empty with prior instances of clinical trials from developing countries with promising results, good sample sizes but which later turned out to be false. Does anybody know of examples or can recommend search terms?