Question DSRDL on native resolution 2560 x 1440.... DL Scaling 1.78x DL (1707x1563) ?

[SMN204]

RTX 4070
Please explain me why I see (1707 x 1365), (1920 x 1563) in DL Scaling DSR settings ? And what do these numbers mean ?
My native monitor resolution = 2560 x 1440 !