Docker/Rocker - unable to locate package python3.8

I am trying to install python3.8 in my container. My base image is rocker/shiny. I was able to build my image and start my container two weeks ago successfully, but am unable to do so today and am getting the following error message:

E: Unable to locate package python3.8 E: Couldn't find any package by regex 'python3.8'

Furthermore, other folks who try to build this Dockerfile on their computers are getting the same error message.

Here is my Dockerfile

# base image
FROM rocker/shiny:3.3.2

RUN apt-get update && apt-get install -y \
    sudo \
    python3.8 \
    python3-dev \
    libpq-dev \
    python3-pip \
    libxml2-dev

COPY . /srv/shiny-server/app

WORKDIR /srv/shiny-server/app

RUN pip3 install --no-cache-dir -r requirements.txt

EXPOSE 3838

CMD ["R", "-e", "shiny::runApp('/srv/shiny-server/app',port = 3838, host = '0.0.0.0')"]

What I've tried:

-Changing python3.8 to python3.8-venv

-Changed rocker/shiny:latest to rocker/shiny:3.3.2