Ionic-vue - is custom backend jwt authentication bad idea?

I am not sure I understand the question. Do you mean persisted pinia? Yes I use that for refresh tokens, all the rest is just session memory in a store, but refresh token stays in localstorage through pinia persisted state

 persist: {
        storage: persistedState.cookiesWithOptions({
            maxAge: 60 * 60 * 24 * 365,
        }),
        paths: ["refreshToken"],
    },