What is 'Num shaders added'

Hi,

I just ported my project from 4.17 to 4.20 and noticed that I’m getting this in material instances:
252895-
I’m nesting a lot of instances and the number decreases as I get closer to parent in hierarchy.
There seems to be no performance impact but then I’m not sure how to profile it really.

Is it a number of siblings or children?
Could you guys please help me to understand what is it and what it actually shows?

Thanks!
TO

I think it’s a number of shader permutations generated when material is using static switches.

Will this affect the performance as this is showing out?