Ollin already stated he bought the Trek secondhand. I don't think they'd honor any warranty here, but I suppose it's worth a shot.

Your original post said you weigh 110 kg. That's 242 lb. Maybe you meant 100 kg / 220 lb. You're still well under the 300 lb. stated limit, though.

A small voice is telling me that a drop bar conversion on an aluminum hybrid designed for hybrid bars might have resulted in you doing more pulling on the bars, thereby putting more stress on the seat tube above the top tube, especially if you hammer a lot and go up a lot of steep hills. If there wasn't enough seatpost in the seat tube as others have stated, this might be a contributing factor.

I don't know if there's ever a way of knowing where there were microcracks in the seat tube to begin with or whether drop bar + hammering caused this. Either way, I wish you the best of luck with your frame.