simulating fast opamp parasitic capacitance stability question

[yefj]

Hello, here again i have a case where the parasitic capcitance of the opamp described in the third minute create a zero that ruins stability.
how exactly this zero ruins stability?
stability by definition is 0dB 180 degree phase shift.
how exactly we get a zero that ruins?
in the other example we added R that created zero that saved stability.
But here why it the opposite?
Thanks.

 

[D.A.(Tony)Stewart]

this is all about moving poles to get order = -1 thru unity gain or 0dB
. Where did you hear or read zero?