Your request was accepted(maybe the request is revoked now). Your request has been accepted.(your request is still in acception now)

"was" = past simple. This describes the past (obviously). "has been" = present perfect. This describes the present, using a past event. The past simple form cannot do this. "Your request was accepted." = simply a report of what happened in the past. However, this could mean that the situation changed (it was later rejected or lost), or other things happened afterwards. "Your request has been accepted." = We have your request now.

The differemce of was/were and has/have been. I think both of them have the same meaning. But has/have been is more clearly in it's meaning.

was .. "still in check, or ( not obviously been received or not / hesitate unlike the case with, has been: it is very clearly accepted but, in fact all have the same objective it's just more to how you put the word correctly "perfect grammar''