Results on Virtual distillation circuits for error mitigation

Hello Pennylane help

I have a problem with the result of my calculation about VIrtual Distilation mitigation that I read from this paper, in february this code produces the first graph but now when I run it the result is on the second graph where the mitigation result can’t be better than noisy. Can you help me to fix this code, I am very grateful for your help.

you can see this code here

first:

second: