With Streamlit 1.46.0 and Python 3.13, a horizontal scrollbar is shown when a simple dataframe and a form submit button are displayed together. It seems to occur only when the form border is hidden. Here is a minimum reproducible example:
import streamlit as st
import pandas as pd
data = {'Name': ['Tom', 'nick', 'krish', 'jack'],
'Age': [20, 21, 19, 18]}
df = pd.DataFrame(data)
with st.form(key='prediction_form', border=False):
st.dataframe(df)
button = st.form_submit_button('Button')