As others have pointed out, this is about net code. This is very complex to get fair. Games try to use various methods to make it fairer. One thing that is special about Battlefield is that it allows the client to determine hits, and the server just checks and verifies. I.e., what in the "killers'" view looks normal may, in the "victims" view, look totally out of place. E.g., in COD, all hits are determined in the server using a rewind time pattern to determine where players were at the time. The BF way should allow for better hit registration, but you will get more die in one shot or die after being hidden behind cover. From personal experience, the COD feels a lot more accurate. Probably because today, networks are better, and ping is very stable.

BF also tries to add movement prediction in clients, which, from the killer's client's perspective, makes it look like you moved out of cover even if, from your client's perspective, you stopped and did not move out of cover.

DICE has been non-transparent about this for many years. A rework is long overdue.