Thornhill (illness) returned to practice with the Browns on Monday, Brad Stainbrook of 247Sports.com reports.
Thornhill missed Saturday's 23-10 preseason loss to the Packers while recovering from an illness, though no starters participated in the game. The 28-year-old is expected to operate as Cleveland's starting free safety in 2024 and it's unclear if he'll see any action this preseason.