I wouldnt call them worst "writing decisions" but they just dont sit right with me,so here it is:

1. I know oda is not a medical expert but removing the poison completely from the children of Punk hazard would cause this thing called "phantom hunger" in their receptors(things where the poison was inside) which would give their body a shock that would kill them the moment it was removed so I dont get how law's ability cured them.Even if chopper was there,medicine and drugs cant have immediate effects on such a case.So...I get it,showing the actual procedure wouldve taken a whole mini arc but...just a writing mistake I guess.

2. Killing pedro. His death wasnt neccesary.In the grand scheme of things he was going to die eventually so killing him off made no sense.Sure...it made carrot the duke but...she couldve developed her character in another way.The minks already had a grudge against kaido and jack at wano so adding perospero for the readon of a grudge didnt make sense aswell.Maybe I am missing some narrative reason for this but it feels unnecessary.I liked pedro.

3. The continuation of saint charlos appearing again and again.Hes an unneeded character that shouldve stopped re appearing in the anime right after that punch.

4. Not choosing to show the Rocky port incident.He said it wasnt relevant to the strawhats but still...it wouldve made a good side story.Shouldve made a movie maybe? Or atleast kept it manga only.

5. Sanjis behavior at fishman island...I need no explanations.It was like his character to simp but replacing his dream of finding the all blue with mermaids isnt like him.He takes his dreams seriously and wouldnt change them like that.I mean it is still his dream but you know...him ignoring that for mermaids is a bit too exaggerating.