I used AI to help write a chapter of my novel and now I do not know if the book is still mine

I have been writing a novel for three years. I hit a wall on a chapter, a transition section that I knew needed to exist but that I had rewritten six times without getting right. I described the scene to an AI, asked it to draft something, read the output, and rewrote it heavily. Maybe thirty percent of the original AI draft survived into the final version.

The chapter is now the best in the book. My writing group said so without knowing how it was produced.

But I have been thinking about it since. If I submit this novel, do I need to disclose that? If it gets published, is it fully my work? The chapter would not exist in this form without the AI draft but it also does not sound like the AI at all after my edits. I do not know where the line is and I genuinely do not think there is a clear consensus yet.