Study compares quality/completeness of reporting between preprints and peer-reviewed articles. Peer reviewed articles were a bit better, but the quality of preprints is in a similar range, they are valid scientific contributions. User GrassrootsReview, in the For all things open science subreddit, 24 Dec 2020
Comparing quality of reporting between preprints and peer-reviewed articles in the biomedical literature | Research Integrity and Peer Review | Full Text User Open_Access_tracking, in the The Open Access Tracking Project subreddit, 14 Dec 2020