You might need to post your material here, also you should check the texture sampler too.
AFAIK, the default behavior is correct, semi transparency blend with anything below it.
this is the result after i build with pack atlas power of two, it still got alias. May be i will try with another custom material not use Is A2C. Thank you
Is A2C is definitely not an option because the aliasing is caused by it, so you should keep blend on.
There is no easy way for the effect you want to achieve, and it’s definitely breaking the rule of blending. I can only think of using inverted sprite mask to cull things out.