BUG: Pandas sets current time if you do not set it

[Jakub-Ner]

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the master branch of pandas.

Reproducible Example

import pandas as pd

hour = pd.DataFrame({"hour": ["09:00", "12:37"]})
hour["hour"] = pd.to_datetime(hour["hour"])
print(hour["hour"].dt.date) # display current time

Issue Description

Pandas sets current time if you do not set it by yourself.

Expected Behavior

if you don't set a date you expect it to be NaN

Installed Versions

INSTALLED VERSIONS

commit : 945c9ed
python : 3.8.10.final.0
python-bits : 64
OS : Linux
OS-release : 5.11.0-40-generic
Version : #44~20.04.2-Ubuntu SMP Tue Oct 26 18:07:44 UTC 2021
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.3.4
numpy : 1.21.4
pytz : 2020.1
dateutil : 2.7.3
pip : 20.0.2
setuptools : 45.2.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.2
IPython : None
pandas_datareader: None
bs4 : None
bottleneck : None
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : 3.5.0
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : 1.3.18
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : None
None

[MarcoGorelli]

I think this is due to dateutil

>>> from dateutil.parser import parse
>>> parse('09:00')
datetime.datetime(2021, 11, 22, 9, 0)

You should specify the format if you expect it to error if it doesn't match the format

[mroeschke]

Correct, this is inherited behavior from dateutil. Closing