[_0w8t]

We do not have good models of the rate Sun has been losing hydrogen especially on scale of billions of years. So from that we do not have a precise answer how heavier was Sun in past. But heavier Sun implies that Earth was closer compensating for the dimmer younger Sun.

As I understand according to the current estimates this not enough to avoid the cold Earth problem, but there are way too much uncertainty. But if we do not have way to read the brightness from geology alone, that can be an answer.