How is Min/Max Equity per day calculated?

I am a new person. And I have a question to send to ctrader team and our community.

In the photo I attached. I see there are times when Min Equity drops to negative -3k but why is the account still trading?

As I understand Balance can be negative but at that point Equity is still positive and guarantee the margin to continue. But in this case Equity is negative.

The question is, when is the Min/Max Equity each day calculated starting and closing the number by day?
thank!