DevContainer buildx re-pulls image although it already exists on the host

• VSCode Version: 1.101.1
• Local OS Version: Win 11
• Remote OS Version:
• Remote Extension/Connection Type: Dev Containers/WSL/Remote - Tunnels/VS Code Server

Every time I rebuild (with or without cache makes no difference) my devcontainer, it pulls all layers of a large docker image again, although docker on my desktop (using Podman Desktop and the Docker compatibility mode) confirms, the image is up to date.

docker pull <my-docker-repo>5-add-polyspace-platform/polyspace:f7cb4fccfe234aaada41543cd16d9a525355be78
b815984ef5af: Already exists
d18de2d57be4: Already exists
4f8983bf0e70: Already exists
6a2531b72d37: Already exists
29b1cc280302: Already exists
19ffb1766630: Already exists
9cdc993505fe: Already exists
d1c45613890f: Already exists
1a38540e491c: Already exists
f90c8eb4724c: Already exists
27a9245833c9: Already exists
455dc6c25f1a: Already exists
59b59c5ba3cc: Already exists
d4e93011809f: Already exists
01a40bec1cb2: Already exists
4f4fb700ef54: Already exists
8ed2c377c09c: Already exists
81c94d6faddf: Already exists
75b2768492d5: Already exists
eb6973bf34a0: Already exists
ca350c38697d: Already exists
a75096340bd0: Already exists
9282d8301856: Already exists
9839e6757baa: Already exists
e5a3dba6df33: Already exists
1fc177a93b61: Already exists
a6b7995f95fd: Already exists
d0d18580a9fe: Already exists
4a5aadc57a73: Already exists
0f77a7aa5515: Already exists
48fb287b0c80: Already exists
2f0c8d1ff166: Already exists
16a27ed27244: Already exists
e06b1bcf5dd7: Already exists
bd68d458afd8: Already exists
093c52f5a0b7: Already exists
d63142f2d971: Already exists
2aa362e93858: Already exists
3c2c500407e9: Already exists
29372f6756f2: Already exists
98fc8231b894: Already exists
29083a573053: Download complete
<my-docker-repo>5-add-polyspace-platform/polyspace:f7cb4fccfe234aaada41543cd16d9a525355be78

When rebuilding the devcontainer, with this config:

{
    "name": "Zephyr Embedded Development Demo Project",
    "build": {
        "dockerfile": "Dockerfile",
        "args": {"DEVCONTAINER_USER": "${localEnv:USERNAME}"}
    },
    
    "mounts": [
        "type=bind,source=/mnt/wslg/.X11-unix,target=/tmp/.X11-unix",
        "type=bind,source=${localEnv:HOME}${localEnv:USERPROFILE}/xchange,target=/tmp/xchange"
    ],
    "remoteUser": "${localEnv:USERNAME}"
}

and this Dockerfile

# Wrapper to create the windows user inside the container
FROM<my-docker-repo>5-add-polyspace-platform/polyspace:f7cb4fccfe234aaada41543cd16d9a525355be78

USER root

ARG DEVCONTAINER_USER=user
RUN echo $DEVCONTAINER_USER
COPY fix_user.sh /tmp/fix_user.sh
RUN chmod +x /tmp/fix_user.sh && /tmp/fix_user.sh $DEVCONTAINER_USER

USER ${DEVCONTAINER_USER}

ENV TERM=xterm-256color
CMD ["bash", "-l"]
SHELL ["bash", "-l"]
ENTRYPOINT [ "" ]

Pulls everything again, why?

[10552 ms] @devcontainers/cli 0.77.0. Node.js v20.15.1. linux 5.15.167.4-microsoft-standard-WSL2 x64.
[10552 ms] Start: Run: docker buildx version
[10625 ms] Stop (73 ms): Run: docker buildx version
[10625 ms] github.com/docker/buildx v0.14.0 171fcbeb69d67c90ba7f44f41a9e418f6a6ec1da
[10626 ms] 
[10626 ms] Start: Run: docker -v
[10636 ms] Stop (10 ms): Run: docker -v
[10636 ms] Start: Resolving Remote
[10640 ms] Start: Run: git rev-parse --show-cdup
[10642 ms] Stop (2 ms): Run: git rev-parse --show-cdup
[11439 ms] Start: Run: docker ps -q -a --filter label=vsch.local.repository=<my-git-repo>.git --filter label=vsch.local.repository.volume=vsc-remote-containers --filter label=vsch.local.repository.folder=zephyr-demo-project --filter label=devcontainer.config_file=/workspaces/zephyr-demo-project/.devcontainer/devcontainer.json
[11458 ms] Stop (19 ms): Run: docker ps -q -a --filter label=vsch.local.repository=<my-git-repo>.git --filter label=vsch.local.repository.volume=vsc-remote-containers --filter label=vsch.local.repository.folder=zephyr-demo-project --filter label=devcontainer.config_file=/workspaces/zephyr-demo-project/.devcontainer/devcontainer.json
[11462 ms] Start: Run: docker inspect --type image <my-docker-repo>5-add-polyspace-platform/polyspace:f7cb4fccfe234aaada41543cd16d9a525355be78
[11489 ms] Stop (27 ms): Run: docker inspect --type image <my-docker-repo>5-add-polyspace-platform/polyspace:f7cb4fccfe234aaada41543cd16d9a525355be78
[11492 ms] workspace root: /workspaces/zephyr-demo-project
[11492 ms] No user features to update
[11494 ms] Start: Run: docker buildx build --load --build-arg BUILDKIT_INLINE_CACHE=1 -f /tmp/devcontainercli-root/container-features/0.77.0-1750700121480/Dockerfile-with-features -t vsc-zephyr-demo-project-ef37398b43aa503131e5aab09377f6a7b427da4781019c7752aec70cb26110ba --target dev_containers_target_stage --no-cache --pull --build-arg _DEV_CONTAINERS_BASE_IMAGE=dev_container_auto_added_stage_label /workspaces/zephyr-demo-project/.devcontainer
[+] Building 0.0s (0/1)                                docker-container:default
[+] Building 1.2s (6/10)                               docker-container:default.
 => [internal] load build context                                          0.0s
 => => transferring context: 1.10kB                                        0.0s
 => [dev_container_auto_added_stage_label 1/4] FROM <my-docker-repo>  386.2s
 => => resolve <my->  0.0s
 => => sha256:bd68d458afd82828a5bd65aac9de16a556b937d6bc2f9ca 533B / 533B  0.2s
[+] Building 1.4s (6/10)                               docker-container:default
 => [internal] load build context                                          0.0s
 => => transferring context: 1.10kB                                        0.0s
 => [dev_container_auto_added_stage_label 1/4] FROM <my-docker-repo>  386.4s
 => => resolve <my->  0.0s
 => => sha256:bd68d458afd82828a5bd65aac9de16a556b937d6bc2f9ca 533B / 533B  0.2s
[+] Building 1.5s (6/10)                               docker-container:default
 => [internal] load build context                                          0.0s
 => => transferring context: 1.10kB                                        0.0s
 => [dev_container_auto_added_stage_label 1/4] FROM <my-docker-repo>  386.5s
 => => resolve <my->  0.0s
 => => sha256:bd68d458afd82828a5bd65aac9de16a556b937d6bc2f9ca 533B / 533B  0.2s
 => => sha256:bd68d458afd82828a5bd65aac9de16a556b937d6bc2f9ca 533B / 533B  0.2s
 => => sha256:3c2c500407e9018cdffdeb1dba1f2eb844859d06317d7d0 188B / 188B  0.2s
 => => sha256:29372f6756f20951de24c099aa21bf071a117205 1.36GB / 1.57GB  1175.9s
 => => sha256:d63142f2d9716ce9e128385eb3d43f9dfa7de88c 73.19MB / 73.19MB  66.3s
 => => sha256:2aa362e9385809116782c0f195fdb904127886f1 1.39GB / 1.76GB  1175.7s
 => => sha256:98fc8231b894103cb6f51470af9acb33e9e1e037 1.28GB / 1.57GB  1175.9s
 => => sha256:16a27ed2724425770a0f4a111a255f18ac24f 148.54MB / 148.54MB  131.4s
 => => sha256:4a5aadc57a7359efba22c03c01bb0afde6b9dd1 866.64kB / 866.64kB  1.2s
 => => sha256:a6b7995f95fd2f86df71495dbc4ba99f96a93f26b112a73 132B / 132B  0.0s
 => => sha256:e06b1bcf5dd794c653c5c483dc96a6d1e8d46212183b63c 221B / 221B  0.0s
 => => sha256:2f0c8d1ff1665978d6722ca168169f760b44d3da21b 2.58kB / 2.58kB  0.0s
 => => sha256:48fb287b0c806aa7e28fb32f02ce9034d55891778e51b49 181B / 181B  0.0s
 => => sha256:e5a3dba6df331b30b28d2815b86a9a96bdd045b7b32a8bd 214B / 214B  0.0s
 => => sha256:9282d83018564db32197c31dea8e5a0649851a5752f546c 323B / 323B  0.0s
 => => sha256:093c52f5a0b79ecca30246c41169d2568be71c07beb1eaf 315B / 315B  0.0s
 => => sha256:0f77a7aa5515b4aa1865a9f82bfb33fb60286f69 53.22MB / 53.22MB  50.4s
 => => sha256:d0d18580a9fefc1c022342865e1e34931d41201b731bfcf 313B / 313B  0.0s
 => => sha256:9839e6757baaed99b19b6a04ec3d5bddb7a02 711.26MB / 711.26MB  598.1s
 => => sha256:eb6973bf34a052d0b5b4c61150ad364b8f48571 398.46MB / 3.66GB  328.0s

When you check the sha256 of the layers being pulled again, my first log shows that they are already present. So why are they pulled again? Do I have to passthrough the socket of the host Docker or something? I think docker buildx build ... is run in the bootstrap image, so why does the bootstrap image not use the host's docker cache?

Thanks!