]The only reasons Zenitsu is held back in his abilities is because he is unable to cope with the death of Gramps, He survived til now not just because of sheer luck (unlike what others and himself believes).
Zenitsu was recognized as a successor alongside Kaigaku by Gramps and survived the Final Selection, No one who survived the Final Selection along with Tanjiro was incapable despite how much Zenitsu wants to believe so. He really had nothing to fight for, unlike Tanjiro or Inosuke who both have their aim set high.
The only times that Zenitsu can toss away his package and blitz pass the past is when he is in a state of unconsciousness, that is not a power-up state, but what he can really accomplish.
In earlier chapters, Tanjiro said he learned ways to be fast like Zenitsu for a short moment because he studied his techniques, Now is this 7th form something Zenitsu took inspiration from Tanjiro? That would be really cool.
(Also it is really cool how both thunder breathing succcessor parted ways just to both be recruited by breath of the sun users[at least i assume Upper Moon 1 is one])
Anyway, Bravo! MA BOY Zenitsu
BTW Is the Lower Moon Still a Thing? Since Muzan did the purge thing I assumed he trashed the role of a Lower Moon.