It means investors as a whole are willing to pay 21 dollars for every dollar of Reddits annual earnings.

Reddit is still increasing it's yearly profit by about 50%, which is a lot. Reddit stock p/e was above 50 because investors were more confident in the stock price continuing to rocket up.

Now investors are concerned about stalling user growth, decreased user engagement, Google's AI search results cannibalizing ad views, and reddit requiring login.