The first numbers on each line's label represent the size that is in your stylesheet, whilst the second represents the computed size on your display. The reason these don't match is because you probably have the scale of your display set above 100% (I think 125% is default on windows), you can change the size to 100% under display settings and you should see that the two values on each line match.

It looks like your screen has 150% scaling, so the computed value for the point you mentioned is calculated as 150/1.5 = 100. This is why you see 150px.100px. The whole browser window is also affected by this scaling, i.e: with 125% scaling, a 1920px by 1080px window will appear as an upscaled version of a 1535px by 864px window.

https://developer.chrome.com/docs/devtools/css/grid#track-sizes