Dashed line round caps don't add additional length to the line as non-dashed line does.
Reporting a bug? please specify Unity version:
2020.3.3f
Reporting a bug? please specify Shapes version:
3.2.3
Reporting a bug? please specify Render Pipeline:
URP
this is because dashes and caps are two separate things
Dashes are rounded internally, and don't add extra length, while the line cap itself does. You can see how it works by changing the dash offset, and you will see that the rounded caps are still there, it's just that the dashes align with the line endpoints, not the outer edge of the caps
square dashes with rounded caps:
rounded dashes with square caps:
rounded dashes with rounded caps: