It appears that Mikel Arteta is out to get Aubameyang who is a serial offender to the club. As a result he was stripped of his captainship and has not been training with the team.
"He argued that as captain, Aubameyang was to be the figurehead of a new era, and as such, he warranted a new deal starting at £250,000-a-week with plenty of incentives on top -- if the vision of success being laid out was realised. Yet in the final days of 2021, Aubameyang finds himself an outcast. He was stripped of the captaincy after his manager publicly questioned his "commitment and passion" for the cause, and sources claim there's a genuine possibility he could leave the club during the January transfer window." - ESPN
"He argued that as captain, Aubameyang was to be the figurehead of a new era, and as such, he warranted a new deal starting at £250,000-a-week with plenty of incentives on top -- if the vision of success being laid out was realised. Yet in the final days of 2021, Aubameyang finds himself an outcast. He was stripped of the captaincy after his manager publicly questioned his "commitment and passion" for the cause, and sources claim there's a genuine possibility he could leave the club during the January transfer window." - ESPN