Hi adrshkm,
the weights of the SequenceClassification head are initialized randomly.
See this page  https://huggingface.co/transformers/training.html
which says

When we instantiate a model with  from_pretrained() , the model configuration and pre-trained weights of the specified model are used to initialize the model. The library also includes a number of task-specific final layers or ‘heads’ whose weights are instantiated randomly when not present in the specified pre-trained model. For example, instantiating a model with BertForSequenceClassification.from_pretrained('bert-base-uncased', num_labels=2) will create a BERT model instance with encoder weights copied from the bert-base-uncased model and a randomly initialized sequence classification head on top of the encoder with an output size of 2.