I'm sure they have metrics at this point on how often real humans take a particular action. If an account is reporting posts higher than some amount X, then shadow ban that account.
Conversely if you are in the business of publishing spam to Reddit, wouldn’t it be useful if you could overwhelm the site with spam such that the people who care enough report all of the spam they see will get banned?
For how much I see people here saying AI moderation can solve this, I frankly think AI tools are likely to be an order of magnitude better at playing offense than defense - producing huge volumes of AI-generated spam/marketing/offensive content that could fool an AI content moderation algorithm on the other side.