I dont really know if it should be called a bug. However while watching F1 races on TV sometimes you can see onboard shots with revcounter, braking and throttle axis and TC. You can see that drivers are using 100% braking power all the way through braking "zone". In LFS while braking you cant brake 100% all the way because you will block the wheels at half of the braking distance, because the speed will be lower thus less downforce and less grip. you have to modulate braking force lowering it at the entry to the corner. I think real F1 cars have braking force limiter cutting braking preasure under low speeds to prevent from blocking the wheels. I think LFs should simulate such system too.
, most drivers have like 5%-10% throttle in while they're braking. Personally, I dont use left-foot braking much but I found that with the single seaters especially, it can really help prevent lock-ups in braking zones so give it a try. Also remember that you dont use full pressure entering the corner, drivers often let the pedal out as they're turning in.