The past that was perceived also isn’t being changed. It stays as it was perceived, in that reality. There is no claim that it magically changes. (What happens is that your decision can determine that reality’s weight/probability to have always been negligible compared to the weight of the other relevant possibilities.)
OK, so this is a more UDT-style framing (which I’m sympathetic to). Then the “alternate realities” part, not the “changing the past” part, was more the one targeted at you. But there are definitely people who think about FDT as “changing the past”, or at least talk about it in that way, so that’s who that clause was targeted at.
The past that was perceived also isn’t being changed. It stays as it was perceived, in that reality. There is no claim that it magically changes. (What happens is that your decision can determine that reality’s weight/probability to have always been negligible compared to the weight of the other relevant possibilities.)
OK, so this is a more UDT-style framing (which I’m sympathetic to). Then the “alternate realities” part, not the “changing the past” part, was more the one targeted at you. But there are definitely people who think about FDT as “changing the past”, or at least talk about it in that way, so that’s who that clause was targeted at.