I see. If the client only checks on upload I wonder if you could add some sort of timeout after which you start dynamically serving the image. That way the upload would succeed but you still get a performance improvement.
Discussion
Some clients check the match (e.g., Amethyst, Snort [though it proxies and changes media itself without asking]) so no can do. Welcome to the land ruled by devs with wrong ideas about what client should or should not do. 🐶🐾🤷♂️