I ended up finishing up a 30K novella, even though 20K is typically where I top out. (Lke my last two unpublished book are sitting at 20K.)
If the the middle and end of your book is stylistically inconsistent with the the first third, do you try to make the second 2/3rd match the first? Or vise versa?
This started out as two 10,000 word novelettes, inferred together by later merging characters that were essentially the same person. So I ended up pantsing a first draft of a 9,000 word sandwich meat that creates the context for the smooth transition to the final third.
As you can see my darting eyes and nosed spectacles, I'm not use to novellas.