Joe Gomez was the first of the Liverpool players to arrive at St. George's Park for England's final two Euro 2020 qualifiers against Montenegro and Kosovo. As he went around the canteen, shaking hands with his teammates, Sterling snapped and said "So you think you're the big man?" He then tried to get Gomez in a headlock, knocking food over from the table. He "behaved like a bit of a child" one person told The Athletic.
The incident lasted only ten to fifteen seconds but was the result of ninety minutes of disdain directed at him from the stands in Merseyside (including chants of "one greedy b*stard" concerning his transfer from the Reds to City in 2015). Sterling was City's best player in the game but did seem agitated throughout - getting into skirmishes with Trent Alexander-Arnold and Virgil Van Dijk, in addition to Gomez. The two made up after the final whistle at Anfield which made the incident at the national team setup even more surprising and shocking to the Liverpool defender.
It is thought to have stemmed from the fact that pictures of the 6'2" Gomez pushing around the 5'7" Sterling went viral on social media - subjecting the City winger to much ridicule. While his England teammates initially thought he was joking, when they realised Sterling was serious, they separated the pair of them.
Gareth Southgate - who has always been vocal about not letting club rivalries dictate terms in the national camp - decided that the incident needed severe punishment. Especially considering it was just before England's 1000th international. The Man City player was initially sent home before it took an intervention from senior England players and an apology from Sterling to Gomez for him to rejoin the team. Eventually the penalty for this was dialed down to suspension from the Montenegro game.
The repurcussions continued into the game which, despite a 7-0 win over the Balkan state was more notable for the boos Gomez got from sections of England fans as he came on for Mason Mount late in the game - something that reportedly upset Gomez massively. Sterling, too, came out in support of his England teammate following the game and criticised the booing.
Club rivalries spilling over into the national team were part of the reason why England's Golden Generation never truly lived up to their name. Southgate and the FA have by and large made sure that isn't the case with this team as they build up to Euro 2020 and beyond. The punishment may have seemed over the top but to some quarters, it may also be necessary to lay down a marker and prevent anything of the sort in the future.