Content type controller v4 can auto assign author with this custom controller wrapper:
/src/api/article/controller/article.js
'use strict';
const { createCoreController } = require('@strapi/strapi').factories;
module.exports = createCoreController('api::article.article', () => ({
// Wrapping a core action (leaves core logic in place)
async create(ctx) {
ctx.request.body.data.author = ctx.state.user ? ctx.state.user.id : null
try {
return await super.create(ctx);
} catch (err) {
ctx.badRequest(err)
}
}
}));