Hi !
The output of the function passed to a batched map should be a dict with the structure {column_name → [list of values per element]}
Can you try this instead ?
tokenized_dataset = dataset.map(
    lambda x: {"input_ids": flaubert_tokenizer.encode(
        x['verbatim'], padding=max_length, truncation=True, max_length=512
    )},
    batched=True
)