Error debugging Python in VS Code: "pythonPath" is not valid if "python" is specified – Docker

I get a prompt with:

Invalid Message: "pythonPath" is not valid if "python" is specified 

and the option to open launch.json. But my launch.json doesn’t contain anything that says "pythonPath":

{
  "configurations": [
    {
      "name": "Docker: Python - General",
      "type": "docker",
      "request": "launch",
      "preLaunchTask": "docker-run: debug",
      "python": {
        "pathMappings": [
          {
            "localRoot": "${workspaceFolder}",
            "remoteRoot": "/app"
          }
        ],
        "projectType": "general"
      }
    }
  ]
}

and this is my tasks.json:

{
  "version": "2.0.0",
  "tasks": [
    {
      "type": "docker-build",
      "label": "docker-build",
      "platform": "python",
      "dockerBuild": {
        "tag": "cachepurger:latest",
        "dockerfile": "${workspaceFolder}/Dockerfile",
        "context": "${workspaceFolder}",
        "pull": true
      }
    },
    {
      "type": "docker-run",
      "label": "docker-run: debug",
      "dependsOn": ["docker-build"],
      "python": {
        "file": "src/main.py"
      }
    }
  ]
}

and the Dockerfile:

# For more information, please refer to https://aka.ms/vscode-docker-python
FROM python:3.9.6-slim

# Keeps Python from generating .pyc files in the container
ENV PYTHONDONTWRITEBYTECODE=1

# Turns off buffering for easier container logging
ENV PYTHONUNBUFFERED=1

# Install pip requirements
COPY requirements.txt .
RUN python -m pip install -r requirements.txt

WORKDIR /app
COPY . /app

# Creates a non-root user with an explicit UID and adds permission to access the /app folder
# For more info, please refer to https://aka.ms/vscode-docker-python-configure-containers
RUN adduser -u 5678 --disabled-password --gecos "" appuser && chown -R appuser /app
USER appuser

# During debugging, this entry point will be overridden. For more information, please refer to https://aka.ms/vscode-docker-python-debug
CMD ["python", "src/main.py"]

all created by the "Docker: Add Dockerfiles to Workspace…" -> "Python: General" command. It worked before but stopped working now. I tried to use Python 3.9.6 image, since that is the one from my .venv but no success. The image gets build without an error and also docker run works fine. The moment it tries to "attach" I get this message.

This is the terminal output:

*  Executing task: docker-build 

> docker image build --pull --file '/Users/philipp/Sites/cache-purger/Dockerfile' --tag 'cachepurger:latest' --label 'com.microsoft.created-by=visual-studio-code' '/Users/philipp/Sites/cache-purger' <

#1 [internal] load build definition from Dockerfile
#1 sha256:c141506ce29f9a418e9f7aa174d1f48de1cda1b771a6710f311fe64b6591e190
#1 transferring dockerfile: 37B done#1 DONE 0.0s

#2 [internal] load .dockerignore
#2 sha256:7b7281b332cffe701548a5bd1f2ad8aa5ef2ad5c7b67d8432ca152c58ad529f9
#2 transferring context: 120B done
#2 DONE 0.0s

#3 [internal] load metadata for docker.io/library/python:3.9.6-slim
#3 sha256:fc1a7a5428ef0e03d295fd81aa9c55606d4e031ac5c881a3941276f70f00d422#3 DONE 0.6s

#4 [1/6] FROM docker.io/library/python:3.9.6-slim@sha256:4115592fd02679fb3d9e8c513cae33ad3fdd64747b64d32b504419d7118bcd7c
#4 sha256:e45c2d35d6435658167a7e046bb6121c498edab8c8777f3cd5a56f585eead583
#4 DONE 0.0s

#5 [internal] load build context
#5 sha256:c20427bc601f92346d0d4519c594683dbcd8b4a64b1ca4f59a16ce42d0f217db#5 transferring context: 176.69kB 0.2s done
#5 DONE 0.2s

#8 [4/6] WORKDIR /app
#8 sha256:cd260eca990853ac7a3228b8435b728cf978b08e035684cf2988a4ce596004e6
#8 CACHED

#9 [5/6] COPY . /app
#9 sha256:8261e563e3b0b0cd32854e76a77543449ceca6f5b3fe76de9cd0a1ea8fae3fab
#9 CACHED

#6 [2/6] COPY requirements.txt .
#6 sha256:3d3741721306ef2859b965575ba3fe04d426fb55b1d22dde909fde88f9be8998
#6 CACHED

#7 [3/6] RUN python -m pip install -r requirements.txt
#7 sha256:92a4bcf37798995b7fcd368e190a189642affda38a1ecc4f004f0827567520e6
#7 CACHED

#10 [6/6] RUN adduser -u 5678 --disabled-password --gecos "" appuser && chown -R appuser /app
#10 sha256:b0b00f3b01ee74a6a813c94699340d78511ccdb89b4b326fd106625803062cb1
#10 CACHED

#11 exporting to image
#11 sha256:e8c613e07b0b7ff33893b694f7759a10d42e180f2b4dc349fb57dc6b71dcab00
#11 exporting layers done
#11 writing image sha256:1a8bf7fd9f7f83ddc25d421eef1c4fb986ef79cdc9bb9709d10ed530c2b4c6c0 done
#11 naming to docker.io/library/cachepurger:latest done
#11 DONE 0.0s *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: docker-run: debug 

> docker container run --detach --tty --name 'cachepurger-dev' --publish-all --mount 'type=bind,source=/Users/philipp/.vscode/extensions/ms-python.python-2023.2.0/pythonFiles/lib/python/debugpy,destination=/debugpy,readonly' --label 'com.microsoft.created-by=visual-studio-code' --entrypoint 'python3' cachepurger:latest <

8baa3597aa97f39641a43f6886b884e139165f83edaca9ae1f99e9f8a760e50e *  Terminal will be reused by tasks, press any key to close it.