Let's say you run a legit network of sites under one umbrella company. Those sites have different content but the content is in the same framework and structure because I assume they use the same content management system and overall site structure. Guess what, if Google assigns a manual action to one site and knows it is part of a larger network of sites, it can apply that manual action across the other sites in the network.
John Mueller of Google was asked if this was possible on Twitter and he said "it's certainly possible -- if they're built the same way, then it would be reasonable to apply the same manual action."
This specific manual action was a thin content manual action. Thin content examples Google gives include automatically generated content, thin affiliate pages, content from other sources such as scraped content or low-quality guest blog posts and doorway pages.
Here are the tweets covering this topic that provide more context:
Google manually reviews one site, can check the footer quickly to see the other sites in the network and scan those for similar or different manual actions.
Forum discussion at Twitter.
