Posts that are published from custom statuses like "Pitch", "Assigned" etc. retain the old date when this status was made instead of the current one.
In my case, editors are catching it some time later when posts are already indexed and change it, and this creates issues with SEO and also a lot of redirect by Yoast Pro because we have the date in URLs. When this issue got our attention in Google Search Console, there was already a huge amount of redirects.
I've added action on 'transition_post_status' hook to update the date, but I this is a workaround and from my point of view looks like the thing that should be handled by the plugin.