http2_push_preload directive stability when upgrading Nginx from 1.19.2 to newer releases

The goal is to enable nginx’s http2_push_preload feature to preload critical assets via the X-Accel-Redirect header while keeping alert noise low by suppressing unnecessary push‑related warnings.

Because the directive is marked experimental, its behavior may change across versions, it interacts with caching layers (potentially causing duplicate pushes when a pushed resource is already cached), and browser support for HTTP/2 server push varies. This creates uncertainty about long‑term reliability and the appropriate logging configuration to avoid notification noise without losing other important alerts.

Will enabling http2_push_preload continue to generate push promises after upgrading to Nginx 1.22.x or later? How can duplicate pushes be avoided when cached resources are involved? What error_log level should be set to suppress push‑related warnings while preserving other critical alerts?