Gatsby - SSR i18n translation are loaded on client - reactjs

Question

I have a multilingual gatsby website, I try to improve the lighthouse performance score, so i followed this guide to generate my page with the translation in the html. Here is my gatsby-ssr.js file
import { renderToString } from 'react-dom/server'
import Backend from 'i18next-sync-fs-backend'
import i18n from "./src/locales/i18n"
const namespaces = [...my ns...];
export const replaceRenderer = ({ bodyComponent, replaceBodyHTMLString }) => {
i18n
.use(Backend)
.init({
initImmediate: false,
backend: {
loadPath: 'src/locales/{{lng}}/{{ns}}.json',
},
})
// load the common namespace
.loadNamespaces(namespaces, (err) => {
replaceBodyHTMLString(renderToString(bodyComponent))
})
}
My i18n.js file :
import i18n from "i18next";
import Backend from "i18next-xhr-backend";
import LanguageDetector from "i18next-browser-languagedetector";
import { reactI18nextModule } from "react-i18next";
i18n
.use(Backend)
.use(LanguageDetector)
.use(reactI18nextModule)
.init({
fallbackLng: "fr",
ns: ['translation'],
defaultNS: 'translation',
load: 'languageOnly',
debug: false,
interpolation: {
escapeValue: false, // not needed for react!!
},
react: {
wait: true,
},
});
export default i18n;
I use the HOC withNamespaces from react-i18next (v8) in my page like that export default withNamespaces('home')(IndexPage);
This works well because the generated HTML has all the text translated but when I access to my page the client will load a second time the translation and re-render the page, this cause a flickering on the page and big layout shift so lighthouse really not like it. I believe this is in relation with i18next-xhr-backend but I'm stuck.
I expect my page to not load the translation on page load, because the html has already the text translated so I don't need to load translation again