Maybe your monitor is set at 50 Hz, so enabling Vsync forces the game to run at 50 fps.
From France with love.
Laptop ROG : W10 / Ryzen 7 4800HS @2.9 GHz (4.2 GHz Turbo disabled unless necessary for better thermals) / 16 Go DDR4 / RTX 2060 MaxQ (6 Go GDDR6)
Laptop ROG : W10 / Ryzen 7 4800HS @2.9 GHz (4.2 GHz Turbo disabled unless necessary for better thermals) / 16 Go DDR4 / RTX 2060 MaxQ (6 Go GDDR6)