If you stringify or write to disk the model with add_comments=True (or with "fields-only") and fields have multi-line comments (with config use_attribute_docstrings=True) or multi-line field descriptions (description="My cool string.\nWith a newline") the output yaml will be malfomed.

from typing import Annotated

from pydantic import BaseModel, Field

class MyModel(BaseModel):
    """My custom model."""  # This will become the header!

    c: Annotated[float, Field(description="See three?\nPO")] = 3  # description will become a comment

will produce

# My custom model.
c: 3.14  # See three?
PO

Likewise something like

c: float = 3
"""
Comment line one
Comment line two
""" 

with attribute docstrings will have the same issue, where Comment line two will be on a newline, and not commented out.

It would appear multi-line model comments work fine.

Version used: 1.6.0