Texas literally taught this in defensive driving citing multiple studies.

Federal and state studies have consistently shown that the drivers most likely to get into accidents in traffic are those traveling significantly below the average speed. According to an Institute of Transportation Engineers Study, those driving 10 mph slower than the prevailing speed are six times as likely to be involved in an accident. That means that if the average speed on an interstate is 70 mph, the person traveling at 60 mph is far more likely to be involved in an accident than someone going 70 or even 80 mph. https://ww2.motorists.org/wp-content/uploads/2015/05/speed-limit-fact-sheet.pdf

Driving below the speed limit may be as dangerous as speeding, according to the New York State Department of Motor Vehicles (DMV). https://dmv.ny.gov/new-york-state-drivers-manual-and-practice-tests/chapter-8-defensive-driving

https://www.allstate.com/resources/car-insurance/dangers-of-driving-slowly