Please help with this edge issue

Hi,

I have a question, I don't know why after using Shape Builder Tool or Pathfinder to cut shapes, then use Transparency, the edge's become like this(Pic no.2). It's been about 2 weeks and it never be like this before(my version is updated, v 26.2.1). If I did something wrong, please correct me

Pic no.1 Using Pathfinder and Transparency

Pic no.2 The edge is not smooth as usual

Thank you in advance to anyone who help me find out!

Thank you