Html style ignored -- Possible bug or is this a feature change

Hi All,

I have been using the Jupiter/minimal-notebook image and have noticed a distinct change in behaviour across the last few versions (6.4.0 versus the behavior of both 6.4.2 and 6.4.3)

The following simple markdown illustrates the problem:
Putting this into a markdown cell

<p style="background-color:powderblue;"> HELLO WORLD </p>

On versions prior to 6.4.2 produce Hello World with a blue background

However, on 6.4.2 and 6.4.3 this no long works and all my notebooks that use style specifications fail to render correctly. The problem seems to be localized to Jupiter-notebook classic as I tested with Lab and it worked as expected.

Is this a intentional change or a bug. And if folks do think it is a bug what steps should I take next.

Details below:

Not working:
Jupyter-Classic
HELLO WORLD
In [2]:

!jupyter --version
‚Äč
jupyter core : 4.7.1
jupyter-notebook : 6.4.3
qtconsole : not installed
ipython : 7.26.0
ipykernel : 6.2.0
jupyter client : 7.0.1
jupyter lab : 3.1.9
nbconvert : 6.1.0
ipywidgets : not installed
nbformat : 5.1.3
traitlets : 5.0.5

Not working:
Jupyter-Classic
!jupyter --version
jupyter core : 4.7.1
jupyter-notebook : 6.4.2
qtconsole : not installed
ipython : 7.26.0
ipykernel : 6.0.3
jupyter client : 6.1.12
jupyter lab : 3.1.4
nbconvert : 6.1.0
ipywidgets : not installed
nbformat : 5.1.3
traitlets : 5.0.5
HELLO WORLD

Working:
Jupyter-Classic
HELLO WORLD
In [1]:

!jupyter --version
jupyter core : 4.7.1
jupyter-notebook : 6.4.0
qtconsole : not installed
ipython : 7.25.0
ipykernel : 6.0.3
jupyter client : 6.1.12
jupyter lab : 3.0.16
nbconvert : 5.6.1
ipywidgets : 7.5.1
nbformat : 5.1.3
traitlets : 5.0.5

Working:
Jupiter-Lab:
HELLO WORLD
[1]:

!jupyter --version
jupyter core : 4.7.1
jupyter-notebook : 6.4.2
qtconsole : not installed
ipython : 7.26.0
ipykernel : 6.0.3
jupyter client : 6.1.12
jupyter lab : 3.1.4
nbconvert : 6.1.0
ipywidgets : not installed
nbformat : 5.1.3
traitlets : 5.0.5

Thanks.