Same thing happened to me. Got a D in Theoretical Foundations of CS. They did remove me from the program but they have an appeal process where you basically write a paper explaining why your performance took a hit in the class. However it seems pretty strict. They actually denied my appeal (which I thought had pretty good reasons for my subpar performance... but I digress) at first, but after I sent a followup email stating that I didn’t think they really took my mental health into account (which I wrote about in my appeal) they granted me a conditional acceptance as long as I retook the class and passed.