What is a homestatic feedback mechanism of Graves disease?

Answer 1

The usual homeostatic negative feedback mechanism of the thyroid hormone is that levels of T4 (and T3) in the blood stream inhibit the release of TSH from the pituitary.

This means that the thyroid doesn't have so much stimulus and makes less T3 and T4

In Graves disease (a form of hyperthyroidism) the thyroid keeps making the T3 and T4 regardless. This drives the TSH level down and makes the T3 and T4 levels high.