Creating a new variable using Set variable activity in one pipeline is creating the same variable in another active pipeline

Here My p2 pipeline has the following variables before.


But when, I am trying to create a new variable using Set variable activity in p1 pipeline, it is creating the same variable in the p2 pipeline as well.


Now, you can see the same variable was created in p2 as well.


It is not the same case when creating the variables by clicking the new in variables list.