IMO, "Systemic Racism" is where a system treats people of a certain race differently because of their race, usually disadvantaging one group and advantaging another.
People often think some system must be "systemically racist" because they look at an end result, see a proportion that is different to the general population, and decide it must be so, and then look for the racism that surely must be there ... when of course it doesn't have to be. Less often noticed, but the "correct" mix doesn't mean that a system isn't systemically racist, it could be.
As an extreme example: is a hospital maternity ward systemically sexist because all of the patients are women? No, there are other reasons for the patients being women.
Is the NBA systemically racist because 75% of the players are black? No, there are other reasons for the players being predominantly black.
The only documented and approved systemically racist system I can think of right now is college admissions, which favours black candidates mostly at the expense of asian candidates.