H(s) in closed loop transfer function incorrect?
I am not familiar with Mathematica.
Your system

G should be of the format \$\frac{V3}{V1}\$. i.e. V1 is input, V3 is output of G(s)
H should be of the format \$\frac{V1}{V3}\$. i.e. V3 is input and V1 is output of H(s).
However, your image seems to show that HofS1 is a function which takes V1 as input and produces V3 as output. I think that this actually represents 1/H(s).
So the line SystemsModelFeedbackConnect(..) is actually doing
\$\frac{G(s)}{1 + G(s)\frac{1}{H(s)}} = \frac{G(s)H(s)}{H(s) + G(s)} \$
So for large values of G(s) (below 10^7 Hz?) you may be effectively plotting H(s) which is supported by the observation that green plot and yellow plot are symmetric about 0 dB.