wp_smush_image_optimised

See hook in action

See this hook used in plugins:

Select Pluginwp-stateless.2.3.2wp-stateless.3.0wp-stateless.3.0.1wp-stateless.3.0.2wp-stateless.3.0.3wp-stateless.3.0.4wp-stateless.3.1.0wp-stateless.3.1.1wp-stateless.3.2.2wp-stateless.3.2.4wp-stateless.3.2.5wp-stateless.3.3.0wp-stateless.3.4.0wp-stateless.3.4.1