For the most part, Monster Hunter Rise hasn't really had much of a presence on PC, as the game has had relatively low player counts ever since it debuted on the platform. However, that has all changed since the release of the Sunbreak expansion, as Rise's Steam player count has tripled its typical peak over the past few days.
As SteamDB notes, ever since Sunbreak launched on June 30, Rise's player count has grown from a usual peak of around 75,000 players to over 230,000 at its height. It should be noted that this player count growth has also seen the game set a new all-time player count peak on Steam, which just so happens to be 231,360 players, which was clocked in yesterday.
As it currently stands, Rise has an active player count of around 110,000 (enough for seventh on Steam's current most-played games list), which is still significantly higher than its usual peak, and way higher than its regular lows of around 30,000 players.