I'm sorry to hear that! I may not be of much help, but I do know a bit in psych. This is not meant to say you haven't already thought of this, just leaving a few suggestions.
Check to see if said student has any history of not following directions, grades suddenly dropping, or just some little things on their file. It really depends on the students age, but it could just be seasonal depression or quarantine getting them down.
The election is right around the corner, so it could just be politics or their family's opinions (that's how it is for me, I haven't spoken to my grandfather for months). Again with politics, if your student is queer and closeted (not trying to assume anything), then it cold be parents, friends, or peers who aren't accepting of them. If your student is a person of color, then it could be all the stuff going on in the media. These really are some trying times, but don't pressure your student to say anything that they don't want to.
Maybe something happened to a family member or friend. Or they have an unchecked mental illness, so they probably aren't taking medication. It could be bullying, abuse or just about anything. Maybe it's just them daydreaming or trying to get a gag out of you getting frustrated over them.
If it bothers you that much, do a little digging yourself, and see if anything has been going on with them over the last couple years. If you don't find anything, or you find something concerning, then just ask them yourself.
I hope this helps, and I hope you have a good day! I'm not qualified in the least to answer these questions, but i'm a bit too aware of things for my age, so I like to think i'm smarter than people in my age group.
If your students grades start to drop, consider speaking to their parent/parents or guardian.