When following the current stylistic installation guide you'll receive an error with adonis eslint config because "@Stylistic" is already declared as a plugin. But sadly the version that is used is the @stylistic/eslint-plugin-ts package that is no longer maintained.

See the text here:

Unified Plugin

We used to provide separate plugins for each language like @stylistic/eslint-plugin-js, but since v5, we have merged them into a single plugin.

Those separated plugins would still work but would not receive new features. Please consider migrating to the unified plugin.

My number one mistake was that I didn't know that adonis already bring Stylistic preinstalled, but to use new rules like array-bracket-newline I have to do weird renamings in my eslint config:

import { configApp } from '@adonisjs/eslint-config';
import stylistic from '@stylistic/eslint-plugin'

export default configApp({
    plugins: {
        // "@stylistic" was already declared in the base config of AdonisJS
        '@stylisticCustom': stylistic // <--
    },
    rules: {
        '@stylisticCustom/array-bracket-newline': ['error', 'consistent'],
        // ....
    },
});

So would be nice that the new "unified" version get used.