X-Powered-By header is used to inform what technology is used in the server side. This is an unnecessary header causing information leakage, so it should be removed from your application.
You can read more about this recommendation here
Fortunately, nuxt-security module hides this header by default so your application is not leaking this information in the response headers.
However, if you prefer not to have this changed, you can always disable this functionality from the module configuration (which is not recommended but possible) like the following:
export default defineNuxtConfig({ modules: ['nuxt-security'], security: { hidePoweredBy: false }})