Transpile of defu back to CommonJS breaks webpack as it doesn't support mixing different types of imports.
Had to solve it using:
- "@nuxtjs/axios": "^5.12.5",
+ "@nuxtjs/axios": "5.13.1",
Not sure if I did roll back to the exact version that fixes the issue, but that was the last working one for the nuxt project I'm working on.

Might be related to #498
Please check also unjs/defu#28