WebElement rect size measurement is wrong during real time test run

The issue is that the WebElement rect has a different size measurements in real time,
When I capture the element with the appium inspector desktop app I get the following measurements:

as you can see the y value is 559

When I capture the element in real time:

the y value is 515

Why is that?
If I hard coded swiping by xstart=100 and ystart=559 it is all ok.