## Context
Console warning `[PostHog.js] was already loaded elsewhere. This may cause issues.` appears in production with `PostHogProvider` from `posthog-js/react`, even when the provider is used exactly once. Reported against Gatsby, Next.js, and Vite apps.

## Verified resolution
Maintainer rafaeelaudibert traced much of it to React StrictMode's double-render in dev and proposed PR #1676 to detect StrictMode and skip the warning. Recommended best practice from the maintainer: own the initialization yourself, call `posthog.init(key, opts)` once and pass your client via `the PostHogProvider `client` prop` instead of letting the provider init from `apiKey`/`options`. Reporters confirmed the warning disappeared after upgrading to 1.231+ and/or switching to manual init; it is otherwise benign (no functional impact reported).