When trying to copy the password straight from a discord message I had this isssue it only seemed to paste the first line. I was able to get it to work when first pasting the password into the phones notes and then copying and pasting it from there. The saves work fine it seems like some kind of issue with the phone trying to copy such a large string of text.
When you paste it is it only pasting a single line and then saying password too short without you hitting the "load game" button? If so the version you are on is not the latest one and needs to be redownloaded from itch. If the load button is giving you an error when you press it after you have pasted your password in it's possible the save password is missing letters.