next-i18next.config.js

const path = require( "path" );

module.exports = {
  i18n: {
    defaultLocale: "en",
    locales: ["en"],
    localePath: path.resolve('./public/locales')
  },
  reloadOnPrerender: process.env.NODE_ENV === "development",
};

TranslationService.ts

import i18next from "i18next";
import { i18n as nexti18next } from "next-i18next";
import { serverSideTranslations } from "next-i18next/serverSideTranslations";

export class TranslationService {
  static translate = async (
    key: string,
    ns: string,
    lng: string,
    args: { [s: string]: string } = {}
  ) => {
    const i18n = !!nexti18next ? nexti18next : await this.create(lng, ns);

    return i18n.t(key, {
      ns,
      lng,
      ...args,
    });
  };

  static t = this.translate;

  private static create = async (lng: string, ns: string) => {
    const { _nextI18Next } = await serverSideTranslations(lng, [ns]);

    const _i18n = i18next.createInstance();

    _i18n.init({
      lng,
      resources: _nextI18Next.initialI18nStore,
      fallbackLng: _nextI18Next.userConfig?.i18n.defaultLocale,
    });

    return _i18n;
  };
}