I am stumbling on this issue:
Why cannot add PPA deadsnakes?
This line in my dockerfile:

RUN add-apt-repository ppa:deadsnakes/ppa

Failing my docker build with:

1.028 Cannot add PPA: 'ppa:~deadsnakes/ubuntu/ppa'.
1.028 ERROR: '~deadsnakes' user or team does not exist.

So I did what the answer was from the other SO-question:

# Define the base image
FROM ubuntu:20.04 AS builder-image

# avoid stuck build due to user prompt
ARG DEBIAN_FRONTEND=noninteractive

RUN apt-get update && 
    apt-get install -y software-properties-common && 
    rm -rf /var/lib/apt/lists/*
RUN add-apt-repository universe 
RUN add-apt-repository restricted
RUN -E add-apt-repository -y 'ppa:deadsnakes/ppa'

Giving me following error:

 => => transferring context: 6.70kB                                                                                                                    0.3s
------
 > [airflow-webserver  5/26] RUN -E add-apt-repository -y 'ppa:deadsnakes/ppa':
0.341 /bin/sh: 0: Illegal option -
------
failed to solve: process "/bin/sh -c -E add-apt-repository -y 'ppa:deadsnakes/ppa'" did not complete successfully: exit code: 2

Does anyone know how i can get my way around this? Thank you in advance