look in “beitzah” ‘bais amud bais” rashi on “koach deheteira odif”
That has no bearing on our discussion. You are implying that it is better to follow a p’sak which is more lenient; Rash”i is saying that one needs more expertise to issue a lenient p’sak, but that does not mean that any stringent p’sak comes from ignorance, chas v’shalom!
R’feivel Kohn did an unbelievable job job in writing “Badei Hashulchan” (trying to follow the mishne berurah’s example).
I specifically meant in ?”? in the ??????? s.v. ???? ????? ????. He discusses the issue of how common fake dairy is today compared to the times of the ??”? and ?”?.