Where is CFBundleUrlSchemas is written?

I am currently working on an update for an older iOS app. Its bundle identifier starts with a number “123myapp” (which is forbidden for new apps). However when I upload the ipa archive to the app store it fails it tells me that I have an invalid identifier “123myapp” for an URLSchema. I think that the issue is that expo adds the BundleIdentifier to CFBundleURLSchemas in the info.plist. I am using turtle to build and SDK 39.

Can someone tell me where I can find the code which writes the CFBundleURLSchemas? Or any other way to prevent expo from doing this?