I finally tested deleting a user. First time in a long time I’ve tested this because I’ve just never had the need to delete a user. This is the way it is currently working in case anyone else is curious...
The user is deleted, but their posts remain. However, the content is hidden. In other words, you'll still see the title of the deleted user's posts, but after clicking into the post all of the content is gone. It looks like this:
Personally, I would rather it be that the content is still there. This way, you do not lose any potentially valuable discussion conversations. Instead, the post is made anonymous since the user shows as "[deleted]." And, I think this could satisfy GDPR because I thought I heard that you can either delete everything about the user, or as long as you make their posts anonymous that satisfies the right to be forgotten. But, I could be wrong.