I’m trying to figure out the source of this currently. From my initial research, I found that RN changed how they load the URI param to use resovleAsset() which comes from Image, but I haven’t personally looked into what method they used before to see if it was a base64 or url piece… I don’t know what commit this landed in, so I haven’t opened an issue for the RN team yet. But it is actually an issue that will have to happen at the RN team level.
For the time being, @xcarpentier we’ll need to find an alternative to load pdfs in a webview on iOS with rn 57+.
EDIT: I’ve opened up a RN issue for this hopefully it gets some sort of traction. https://github.com/facebook/react-native/issues/22416