You can't tell the users that acted on a post from the mere UUID of the post itself.
Knowing that this is HN thread 30427711 doesn't give you a set of users who acted on that. For example, a hyperlink to this thread, or posts within it, is not personal data.
You'd have to go to the HN server and ask them for the data - which is personal data, but the post ID itself is not, it's just a handle.
Assigning UUIDs randomly instead of sequentially strengthens this further because there is no way to pull out even a time component from the post ID.
Knowing that this is HN thread 30427711 doesn't give you a set of users who acted on that. For example, a hyperlink to this thread, or posts within it, is not personal data.
You'd have to go to the HN server and ask them for the data - which is personal data, but the post ID itself is not, it's just a handle.
Assigning UUIDs randomly instead of sequentially strengthens this further because there is no way to pull out even a time component from the post ID.