Comparing Pre time skip Luffy to other pirates with 300m bounties, I definitely think this one doesn’t fit his actual threat level. Maybe you can justify with the Nika fruit boosting him but idk that seems off as an excuse.
So from Ennis Lobby to Post time skip is when I’d say his bounty wasn’t reflecting his real threat level.
300 mil
-defeated the strongest Cp 9 dood hyped by Vice admirals
- infiltrating Enieslobby one of the 3 scared integral places owned by Marines
-Waging war on the world government by burning its flag
- Surviving a Buster Call
- Destroying a Navy warship
- Government being haunted by the fact that Luffy is heading to TB and might take down morai as well so had to send Kuma
you realize how huge the stakes were pre TS when zoro's already in 100 mil territory and Snaji is already 77 mil
Plus you can also assume Aokiji had a hand behind the bounties too given he was behind Spandam was under his influence.
And like i reckon jimbe said.. it get harder to get any increase when you're 300 mil already and it was the case after TS.. he just had 400 mil after all that he did in Impel down and Marine Ford.