It's worded as negative for their bait-click but Proton offer a service like Have I Been Pwned but with acces to many more leaked database, by actively searching on the darkweb before the leak is publicly annonced and even if it's kept hidden by the company impacted.
Good clarification, I thought the same thing. Terrible headline.
"Now, the Swiss-based internet privacy outfit Proton has confirmed that it has uncovered a total of 300 million credentials, with passwords appearing in 49% of them, using a new dark web Data Breach Observatory tool."