AES 256 ofb encryption/decryption not working with Openssl3.0

Question

Currently we are using openssl1.1 for a file encryption/decryption.

We are facing a problem when we migrate to opensl3.0.

Below is the code flow used to encrypt the file.

    // Set up the encryption context
    const EVP_CIPHER *cipher = EVP_aes_256_cbc(); // Using AES 256 in CBC mode
    EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
    EVP_EncryptInit_ex(ctx, cipher, nullptr, (const unsigned char *)key.c_str(), null);
    // Encrypt the data    
    int len;
    unsigned char buffer[1024];
    EVP_EncryptUpdate(ctx,buffer,&len,(const unsigned char *)plaintext.c_str(), plaintext.length());  
    ciphertext.insert(ciphertext.end(), buffer, buffer + len);
    // Finalize the encryption
    EVP_EncryptFinal_ex(ctx, buffer, &len);
    ciphertext.insert(ciphertext.end(), buffer, buffer + len);
    // Clean up
    EVP_CIPHER_CTX_free(ctx);

And in a similar way we have done the decryption also.

The same code is not working with openssl3.0, we identified that passing a valid IV instead of NULL is working fine in openssl3.0.

We understand that IV should be a random number, but passing null was working fine in openssl1.0.

Is there anything changed in openssl3.0 related to IV ?

We tried using valid IV instead of null, it is working fine.