Steam UI Scaling

2560x1440@170 125% Scaling + 3840x2160@60 175% Scaling. As can be seen, it appears smaller than Steam's scaling factor of 150% would indicate, implying it's scaling based off of the scale of the second monitor.

2560x1440@170 125% Scaling + 2560x1440@60 125% Scaling. As can be seen, it scales at an expected level. (Note: I would not actually use it at this scale it's just for demonstration purposes)