Alright, I never thought with my ignorance it would be take much time to setup let’s encrypt certificate xD
I didn’t read carefully arch wiki and not enable certain required module which is why it takes so much time to realize the problem.
and trapped in X,Y problem, that the actual problem is I execute the certbot --apache command not in the root directory of web server (*facepalm)
and yeah, now the back button works, even though I solve the problem, but I still haven’t gotten an answer to the previous question, it remains a mystery.