We aren't really aware of how DeBrincat's time in Chicago ended, despite him performing better then ever he was still traded away for an underwhelming return.
One thing that once gained attention was when DeBrincat and Kane got into quite the heated argument, where it would end with DeBrincat telling Kane to ''Shut the f*** up''.
Many speculated this may have caused issues and may be a reason as to why DeBrincat was traded, but that is definitely not the case as arguments are a common thing in the game of hockey.