Conflict between save and write

[inwardmovement]

After installing next and prettier:

npx create-next-app@latest
npm install --save-dev --save-exact prettier
node --eval "fs.writeFileSync('.prettierrc','{}\n')"

When I save tsconfig.json, it's formatted from this (extract):

... "lib": ["dom", "dom.iterable", "esnext"], ...

to this:

...
"lib": [
  "dom",
  "dom.iterable",
  "esnext"
],
...

When I run npx prettier . --write, it's formatted back to:

... "lib": ["dom", "dom.iterable", "esnext"], ...

Where does the conflict come from, between the format on save and write commands?
Both should use the same local node module and config, so have the same result.
I use VSCode with the Prettier extension.

[fisker]

You should config the editor.defaultFormatter https://stackoverflow.com/questions/63954584/how-to-make-prettier-the-default-formatter-in-vs-code

[inwardmovement]

Oops I thought I did, but I had this:

"[jsonc]": {
  "editor.defaultFormatter": "vscode.json-language-features"
},

Thanks!