Since IGT not included, I did a rough estimate via last seen IGT and counting total cutscene time from that point. This isn't accurate but should be close

Math: 1:21:39 = 1:19:33 IGT (Kills Last Rope Shiren Maiden) [Last IGT shown when exiting menu] RTA to IGT at this point = 2:06 difference

1:21:51.65 -> 1:21:54.02 (2.37 seconds) (Cutscene before Mirror Pedestal) 1:22:02.92 -> 1:22:03.61 (.69 second) (Cutscene at mirror before final fight) 1:22:39.04 -> 1:22:40.20 (1.14 seconds) (Cutscene after Kirie is defeated)

4.20 seconds of cutscenes

1:22:51 = 1:20:45 IGT - 4.20 seconds of cutscens = 1:20:41 IGT