Does using a stolen cookie allow you to bypass account 2FA in Slack? Or did EA's slack not enforce 2FA for all accounts? I feel like this is an important quest

Does using a stolen cookie allow you to bypass account 2FA in Slack? Or did EA's slack not enforce 2FA for all accounts? I feel like this is an important question because if the former, the security lapse here is on Slack; if the latter, it is on EA.