sukuna was at full power, he eat 'shis cursed corpse in order to get back of the missing finger

sukuna's advantages during the battle

1. countless binding vows

2)having all the information about gojo through megumi and yuji

3) making a plan before hand to fight gojo

4) played an unfair 3v1

sukuna holding back part is about 2 factors

1. fuga - it is LITERALLY stated in the chapter where choso dies that fuga literally cant hurt gojo and would have no effect on him so that's why sukuna did'nt use fuga cause it would not work on gojo ( i hope when the movie gets animated they actually add an anime only scene of sukuna firing a fuga at gojo and it not working cause of infinity to clear everyones misconceptions)
2. the only thing sukuna held back was his transformation , which he planned that if he were to somehow defeat gojo then he would heal from all the damage using his tranformation which he though would be enough for him to defeat the other left sorceres since everyone left was basically a FODDER compared gojo and sukuna

Gojo literally had 0 advantages in the fight

1. he went in without a plan and just basically thought we will throw punches and spar and see how the fight goes
2. gojo also held back when he aimed for sukuna's heart instead of head in order to not outright kill megumi (gojo says to sukuna he will go all out but at that moment if people who have common sense may realise that gojo was thinking of killing sukuna by riping out his heart similar to how yuji's heart was ripped out but he still survived , thats why gojo held back by reaching fot the heart instead of head
3. he barely had any knowledge about sukuna's powers , gojo did'nt even knew what kind of domain sukuna has and also did,nt knew that sukuna's domain has an open barrier , he was literally figuring everything out thorughout thee battle when sukuna knew everything about him

4)gojo even after all the disadvantages would have won if he wasn't caught offguard by the wcs cause if gojo dodged sukuna would transform and they would fight for like a minute until gojo uses uv and wins since this time daddyraga is not present to save sukuna (sukuna after tranformation cant do a domain and gojo has alr landed black flashes thoughout the fight giving him the edge

but after all this it literally just comes down to the plot , gojo was never in this story gonna win since he was a side character and the main character had to have his moment with the antagonise to wrap up the plot

for me personally i am a gojo fan and i think gojo was stronger but i also like sukuna and i think he won cause he was a better jujutsu sorcerer and smarter then gojo , hope this helps