Extended Absence Essay Question?

Hello!
I am an incoming senior with a GPA of 85.625 or 3.0 and SAT score 1560 (yes, an odd matchup). My relatively low gpa is to blame, in large part, because in my freshman year I was absent for three of four quarters due to mental illness. I failed 2 of the 4 classes I had on my transcript by the end of the year and got a 69 and 78 on the other two. Without my freshman year, my GPA is 91.67 or 3.7.
It is obviously necessary for me to include a response to the essay question pertaining to extended absences that is on most applications, but I don’t know if whether or not it is advisable to be open about the circumstances.
Should I tell schools that I was absent due to depression/mental health issues in my explanation essay, or will this lower my chances of admission?

I have had good grades and taken part in extensive extracurriculars every year following my freshman year, which might ensure my ‘stability’ to schools? I have heard conflicting views on this. Some say that it is a red flag to any school to mention a history of mental illness, and other say that schools will assume the worst if I am vague and describe it as an ‘illness’, and that it is better that I explain properly. I am very conflicted.
Any advice is appreciated.

Perhaps say that you had medical issues that caused you to miss a significant amount of school freshman year and leave it at that. Mental health issues do raise a red flag for many colleges.

I totally agree with @happy1 . Unfortunately there is a a stigma associated with mental health challenges when applying to colleges. (I personally feel this stigma is unjust, but sadly it persists.) As such, you should just say that you had serious health problems freshman year which have since been addressed. It is perfectly fine to be vague. It is not their business what your health condition was/is. Mental illness is just as devastating as cancer, or heart problems, or any other disease.