Many changelogs not showing

In The Hub, open site, go to Plugins, select a single plugin, then click Changelog. Many of the plugins do not offer a changelog. But even when the data is missing from the Hub, it is present in the WP.org page for the plugin at wordpress.org/plugins/plugin-name/#developers

Where exactly is this data sourced from, and what can we do to help ensure that we can see the changelogs here - like, ask developers to post their logs in some specific way? At this point I don't know if Dev isn't sourcing data properly or if other developers aren't doing everything they need to do. Thanks.