On ESPN's pregame show prior to the Week Three Lions-Ravens game, Adam Schefter reported that the Lions had asked the league to monitor low blocks on defensive end Aidan Hutchinson, as the Lions were supposedly concerned that both the Packers and Bears had been hitting Hutchinson low in the first two weeks of the season.
Original Source:
https://www.nbcsports.com/nfl/profootballtalk/rumor-mill/news/dan-campbell-rips-bogus-report-that-lions-complained-about-low-hits-on-aidan-hutchinson