wp_ajax_nopriv_jetpack_upload_file

See hook in action

See this hook used in plugins:

Select Pluginjetpack.6.2.1jetpack.6.4.2jetpack.6.5jetpack.6.6.1jetpack.6.7jetpack.6.8jetpack.6.8.1jetpack.6.9jetpack.7.0jetpack.7.0.1jetpack.7.1.1jetpack.7.2jetpack.7.2.1jetpack.7.3.0jetpack.7.3.1jetpack.7.4jetpack.7.4.1jetpack.7.5.1jetpack.7.5.3jetpack.7.6