Players, staff and officials engaged in shorter and less extensive emotional behavior and interactions, such as arguments and discussions in games played during the 2020 COVID-19 pandemic, when supporters were absent. The findings are presented in a case study of 20 FC Redbull Salzburg championship group games published in Humanities and Social Sciences Communications.
source https://phys.org/news/2021-01-absence-football-altercations-pitch.html