I am using legacy api and it seems to work in iOS 15 as well. tested on real device. let encodedCapacity = 1_000_000 let encodedDestinationBuffer = UnsafeMutablePointer<UInt8>.allocate(capacity: encodedCapacity) defer { encodedDestinationBuffer.deallocate() } let decodedData: Data = withUnsafeBytes { encodedSourceBuffer in let typedPointer = encodedSourceBuffer.bindMemory(to: UInt8.self) let count = compression_decode_buffer(encodedDestinationBuffer, encodedCapacity, typedPointer.baseAddress!, count, nil, COMPRESSION_BROTLI) return Data(bytes: encodedDestinationBuffer, count: count) } return decodedData

Any updates on this? @jberry-w Did you filed a bug report on this?