Add the "max_length" parameter to the Generation configuration.
The 12B model does not match the performance of the 1.2B model as the generation defaults to the max_length of "20". This results in shorter sequences than the model should be generating. For example on WMT14-DE-EN: the 12B model scores 15.52 and the 1.2B model scores 31.786 (SacreBLEU). The default max_length is properly set in the smaller models (see https://huggingface.co./facebook/m2m100_1.2B/blob/main/generation_config.json) and the 12B models should match this. I am submitting similar PRs for the other 12B models.
you can directly add the specified parameter "max_length=2048" to the generate function.generated_tokens = model.generate(**encoded_en, forced_bos_token_id=tokenizer.get_lang_id("zh"), max_length=2048)
That is a shorter term solution when the "out of the box" interface for 12B should match the smaller models.