Generally, astrophysicists say that the young Sun was only about 70% as warm as today, which leads to the alleged 'Faint young Sun paradox' about how a young Earth could have been as warm as it (again, allegedly) was....
BUT, other astrophysicists say the early Sun was MORE radiative, which leads to the alleged 'paradox' of Earth's water source(s)... (I.e., how Earth could have gotten its water many years AFTER its formation, because the energetic young Sun's radiation meant the inner solar system was hot and dry...)
Huh? Which was it?
From The Economist Magazine: Science & Technology December 4th 2021
The memory of water
To find the origin of the oceans, look in outer space
Earth--the quintessential blue planet--has not always been covered by water. Around 4.6bn years ago, in the solar system's early years, the energetic young sun's radiation meant the zone immediately surrounding it was hot and dry. Earth, then coalescing from dust and gas in this region, thus began as a dedicated rock. .......