I don't know what everyone else is talking about, but a fellow student asking how you are performing academically, either deliberately or unintentionally arrogantly, how is that truly a 'toxic person' that causes 'a bad experience' and puts you 'through a lot of trouble'?

Are you failing classes or honours and he/she rubs it in?

On the face it sounds like a tactless person if wrongly assuming you two have a friendly competition going and is oblivious to the fact you find that annoying/demeaning.

But it seems there is more going on, but you don't tell me enough to tell what it is.

A person really has to say "Did you fail last exam again?" to be intentionally bullying. A person may just want to know they scored better than you did, but are not socially able to hide it from you. Are you both scoring good marks? A bit of competition isn't bad. Maybe this boat sailed long ago and maybe it was a one way street anyway, but you could have studied together, help each other, then compare grades.
If this person selected you to be her/his competitor, in a sense that's a compliment. She/he likely respects your academic ability. Otherwise, they wouldn't care. Or only ask it sarcastically to bully you for scoring lower. But if that is what is happening, I think you would have worded it differently.

So yes, why you say it is toxic and causing very bad experiences, I am not sure.

I am also a student and it took me some time to learn that you have to be very careful talking about marks when you score high marks. Basically, it is not nice to ask someone what their mark is if you know they know you likely scored higher.