At roughly the 3:25 mark Stipe lands a decent overhand right to the ear. Not even close to his best shot.
Then at the 2:19 mark he lands a nice right to the jaw. But it's just an arm-punch and is at best 75% power.
At the 2:01 mark he hits a hard right. This is the hardest punch he hits in the first, but is far from his best shot.
At 0:45 he hits another right, but it's more to back Ngannou up than do damage.
In the final ten seconds he tosses a few nice straight punches that are quite good. But not great. The hardest one here is the straight left but Ngannou is at the very very end of the punch and this saves him from taking too much damage.
In all he landed a few nice shots, but none were devastating. The only one that looked to be a fight-ender was in the final exchange of the round, as noted, Francis is just out of range for it hit perfectly. If he had been one step closer that would've been, as you put it, one of his best shots.
Woa there, buddy. You might just run into someone that didn't just watch it the night of, but has watched it three times since, and has it on his HDD... It's okay to be wrong. Just relax and move on with your day.