Wheatstone Bridge Single-Element Varying
For a 0.1% change in one R, you expect only a 0.05% change of total R+R current on that side only.

But since the voltage on either side was 50% of Vb or 5V, you might expect 0.05% of 5V = 2.50mV as the differential voltage.

But KVL proves otherwise with a linearity error of 0.5% / %ΔR full scale ;

from KVL, \$\dfrac{R+ΔR}{2R+ΔR}=\dfrac{ΔV}{V_B}\$