Avoid useless vector coping by move semantic and using referenceness qualifier

For example:

const std::vector<uint8_t> &BlaBla::toBuffer() const {
  return data_;
}

If we use it to make BlaBla and get std::vector<uint8_t> from that and that all.

std::vector<uint8_t> vec = BlaBla().toBuffer(); // <= copy here

Will be better to use ref-qualifier to move data from sigle-used temp object:

const std::vector<uint8_t> &BlaBla::toBuffer() const & { // <= method for case of usual object
    return data_;
  }
std::vector<uint8_t> BlaBla::toBuffer() const && { // <= method for case of temp object
  return std::move(data_);
}
std::vector<uint8_t> &BlaBla::asBuffer() { // <= method to access internal vector
  return data_;
}
const std::vector<uint8_t> &BlaBla::asBuffer() const { // <= method to RO-access internal vector
  return data_;
}

Start by searching the codebase for BlaBla::toBuffer and the data_ member, then inspect how callers obtain buffers from temporary and non-temporary objects. Use the issue’s ref-qualified toBuffer and asBuffer examples as the behavioral target, and verify that temporary use avoids an unnecessary copy while ordinary access remains available.