“Media Bias/Fact Check rarely conducts original fact checks as many other sources are faster and do a better job. We primarily rely on fact-checkers affiliated with the International Fact-Checking Network (IFCN).”

Source: Media Bias Fact Check

Writers at the Poynter Institute, which develops PolitiFact, have stated that “Media Bias/Fact Check is a widely cited source for news stories and even studies about misinformation, despite the fact that its method is in no way scientific.” In 2018, a writer in the Columbia Journalism Review described Media Bias/Fact Check as “an armchair media analysis” and characterized their assessments as “subjective assessments [that] leave room for human biases, or even simple inconsistencies, to creep in”.

Source: Wikipedia