San Francisco/New Delhi, April 1 : In a startling revelation, a group of Meta engineers has reportedly identified a "massive ranking failure" that exposed nearly half of all Facebook News Feed views to potential "integrity risks". According to a report in The Verge citing an internal Meta report on the incident, the software bug exposed the Facebook News Feed via its downranking feature to potential "integrity risks" over the past six months. A Meta spokesperson confirmed the incident, saying the social network "detected inconsistencies in downranking on five separate occasions, which correlated with small, temporary increases to internal metrics". Downranking is a method to enhance the quality of News Feed and has been used in response to wars and controversial political stories, sparking concerns of shadow banning and calls for legislation, the report said late on Thursday. According to The Verge, Meta engineers first detected the vulnerability in October 2021 when a spurt in misinformation began flowing through the News Feed. Instead of curbing posts from repeat misinformation offenders that were flagged by third-party fact-checkers, News Feed allowed posts to be distributed, spiking views by as much as 30 per cent globally. In addition to posts flagged by fact-checkers, the internal probe found that owing to the bug, Facebook's systems "failed to properly demote probable nudity, violence and even Russian state media the social network recently pledged to stop recommending in response to the country's invasion of Ukraine". "We traced the root cause to a software bug and applied needed fixes," said the Meta spokesperson. In October last year, Facebook began to demote all Group content from people who have violated its policies elsewhere on the platform. In a blog post, the tech giant said it added a new 'Flagged By Facebook' feature that shows group administrators' content, which has been flagged for removal. /IANS