complaints from Qarabağ's Gara Garayev that several Celtic players mocked them during a Champions League qualifying, with Brown described as being "the worst". After a game against Celtic in January 2018, Hearts manager Craig Levein criticised Brown for a challenge that injured Hearts player Harry Cochrane. Levein claimed that opponents, particularly younger players like Cochrane, needed greater protection from referees when facing Brown. Levein, who coached Brown when he was Scotland manager, said that Brown was "aggressive" and was responding to a recent fixture where Hearts had beaten Celtic. However, Hearts' captain Don Cowie stated that Brown was not to blame for Cochrane's injury. The following month, Aberdeen's Sam Cosgrove was sent off for a reckless tackle on Brown, to which he reacted by jumping to his feet and 'strutting' towards the crowd while laughing to demonstrate his toughness. Before the end of the campaign, Brown received two foul challenges in which the perpetrator appeared to deliberately stamp on his groin area: Andrew Davies of Ross County was ordered off at the time, with Brown stating "I didn't want more kids anyway" but later adding that "Stamping on opponents when the ball is nowhere near you is definitely not being a hard man or going into a hard tackle"; the referee took no action against Steven Naismith of Hearts at the time, but the Scotland forward was later banned by the SFA. On the latter incident, Brown commented "I think they try to wind me up and get me sent off but let's be honest, I am past that stage and have matured eventually. So it is not going to work." Brown's habit of antagonising opponents was a prominent feature of the 2018–19 season in which Celtic retained all three domestic trophies for the third campaign in succession. His actions during and after an important league match against Rangers that Celtic won to virtually secure the title drew the attention of both the police and the football authorities – although ultimately he was not sanctioned with any offence. He was also criticised for appearing to mock and goad opposing players in the closing stages of the League Cup victory over Aberdeen and the Scottish Cup triumph against Hearts. After Rangers player Glen Kamara was racially abused by Slavia Prague player Ondrej Kudela during a UEFA Europa League match in March 2021, Brown made a public gesture of support for Kamara