It is at least longer than the sequence A."
encoded_sequence_a = tokenizer(sequence_a)["input_ids"]
encoded_sequence_b = tokenizer(sequence_b)["input_ids"]

The encoded versions have different lengths:
thon

len(encoded_sequence_a), len(encoded_sequence_b)
(8, 19)

Therefore, we can't put them together in the same tensor as-is.