I encountered the same issue and resolved it using the following steps:

post_install do |installer|
  react_native_post_install(installer)

  # Path to bitcode_strip
  bitcode_strip_path = `xcrun --find bitcode_strip`.chomp

  def strip_bitcode_from_framework(bitcode_strip_path, framework_relative_path)
    framework_path = File.join(Dir.pwd, framework_relative_path)
    command = "#{bitcode_strip_path} #{framework_path} -r -o #{framework_path}"
    puts "Stripping bitcode: #{command}"
    system(command)
  end

  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings["ONLY_ACTIVE_ARCH"] = "NO"
    end

    if target.name == 'YourFramework'
      device_framework_path = 'Pods/YourFramework/YourFramework/YourFramework.xcframework/ios-arm64_armv7_armv7s/YourFramework.framework/YourFramework'
      simulator_framework_path = 'Pods/YourFramework/YourFramework/YourFramework.xcframework/ios-arm64_i386_x86_64-simulator/YourFramework.framework/YourFramework'
      
      # Strip bitcode from both binaries
      strip_bitcode_from_framework(bitcode_strip_path, device_framework_path)
      strip_bitcode_from_framework(bitcode_strip_path, simulator_framework_path)
    end
  end
end

Explanation:

1. Bitcode Stripping: This script uses the bitcode_strip tool to remove bitcode from specified frameworks.
2. Paths: Make sure to replace 'YourFramework' with the actual name of your framework.

Reference:

For more context, you can check this Bitrise discussion.

Thanks!

What is bitcode?

Bitcode is an intermediate representation of an app’s compiled code that allows Apple to optimize app performance and compatibility.

With Xcode 16, Apple has deprecated bitcode for all platforms, meaning that builds with bitcode enabled are no longer accepted.

Execute this command in Pods folder of your project:

xcrun bitcode_strip -r USED_FRAMEWORK.framework/USED_FRAMEWORK -o USED_FRAMEWORK.framework/USED_FRAMEWORK

Note:

Replace USED_FRAMEWORK with your own used framework name.

Example:

xcrun bitcode_strip -r Pods/FBSDKLoginKit/XCFrameworks/FBSDKLoginKit.xcframework/ios-arm64/FBSDKLoginKit.framework/FBSDKLoginKit -o Pods/FBSDKLoginKit/XCFrameworks/FBSDKLoginKit.xcframework/ios-arm64/FBSDKLoginKit.framework/FBSDKLoginKit

Repeat this command for your all used frameworks which are reported as “contains bitcode” in the errors/logs panel when you’re uploading app to AppStore.