The Players Championship may be a Signature Event, but it's one of just three total to still have a cut. The rest of the elevated events do not to ensure the top-notch field plays all four days, but with over 140 players playing, this particular tournament decided to roughly halve the field after two rounds.
The cut line changes all the time, with each player's performance determining where the cut moves. It's designed to be the top 65 players and it accounts for ties, so whenever a player inside or outside the top 65 makes a move up or down the leaderboard, things change.
As a result, things can change even now. The round will end fairly soon, but it's not over yet. Because of that, this is only a projected cut line, not the final one. Right now (at the time of writing), there is, per Data Golf, a 61.9% chance that -1 ends up being the cut.
There is also a 36.3% chance that even to par ends up being the cut. There's a small, 1.7% chance that -2 is the cut, but the other two are much more likely given how everyone's performed so far.
That means that, based on the projected line at the Players Championship, several golfers are in danger. The cut line of -1 would mean that Justin Rose, Laurie Canter, Ludvig Aberg, Russell Henley, and Rico Hoey would go home early.
If it ends up being even, then those players would be safe, but Shane Lowry, Joel Dahmen, Michael Kim, and Hideki Matsuyama would all go home, and they might no matter what.
As it stands, Wyndham Clark, Justin Thomas, Viktor Hovland, Tony Finau, Max Homa, Nick Dunlap, and Matt Fitzpatrick are all but assured of missing the cut. In some cases, like Dunlap who is in last place, it's a guarantee already.
Who's the new betting favorite for the Players Championship?
The opening favorite for the Players Championship was back-to-back champion Scottie Scheffler. The odds liked his chances of winning a third time in a row, but that has changed after two rounds.

Per the PGA Tour, the new favorite is Rory McIlroy. McIlroy (+360) was just behind Scheffler and is currently tied for fourth, so his odds haven't changed very much after two.
He is immediately followed by Collin Morikawa, who is now +400 to win and is also tied for fourth. Co-leaders Akshay Bhatia (+600) and Min Woo Lee (+700) had their odds skyrocket.
Scheffler, despite shooting five under on the weekend, had his odds grow to +1200, so he's not a long shot but is not the favorite any longer.