Same value for the materialInstance parameter, but got different visual effects in similar range

[yicong123456]

I used the same lineWidth in materialInstance for render object in the screenshot below.But the result seems different(the lines on the left range seems has larger lineWidth than the lines on the right).

This is the mat file where I used the lineWidth in materialInstance:

normal.xy *= 0.5 * materialParams.lineWidth;
position.xy += normal.xy * side;
material.worldPosition = float4(position, 1);

and the side is used to tell whether to add or subtract the value

When I increase this variable lineWidth(nothing changed except the value of lineWidth), the result rendered still doesn't look correnct, but compared to the previous image, their lineWidth seems to have increased proportionally campare with the previous screenshot above. Can someone help me understand the reason for this phenomenon and what the underlying principles are? Thanks so much!