I got the same issue before.

To solve this problem, you should use F1 > Dev Containers: Rebuild Container rather than F1 > Dev Containers: Rebuild Container Without Cache.

Then it should be able to use a local image. Tested on my local and worked fine.

I was wondering about the same thing, so I did the following:

Steps

1. I printed out the image history, only printing out the column that shows the actual docker file statements. See https://docs.docker.com/config/formatting/ and https://docs.docker.com/engine/reference/commandline/history/

docker image history PUTIMAGE_HASH_HERE_FOR_IMAGE_NOT_ENDING_IN_UID --no-trunc --format "table {{.CreatedBy}}" > image_wo_uid.txt

docker image history PUTIMAGE_HASH_HERE_FOR_IMAGE_WITH_UID_AT_END --no-trunc --format "table {{.CreatedBy}}" > image_uid.txt

2. Then diff the two: diff image_wo_uid.txt image_uid.txt

3. That gives you something like (note: reverse chronological order):

1a2,9
> USER vscode
> ARG IMAGE_USER
> RUN |3 REMOTE_USER=vscode NEW_UID=1000 NEW_GID=1000 /bin/sh -c eval $(sed -n "s/${REMOTE_USER}:[^:]*:\([^:]*\):\([^:]*\):[^:]*:\([^:]*\).*/OLD_UID=\1;OLD_GID=\2;HOME_FOLDER=\3/p" /etc/passwd);  eval $(sed -n "s/\([^:]*\):[^:]*:${NEW_UID}:.*/EXISTING_USER=\1/p" /etc/passwd);  eval $(sed -n "s/\([^:]*\):[^:]*:${NEW_GID}:.*/EXISTING_GROUP=\1/p" /etc/group);  if [ -z "$OLD_UID" ]; then   echo "Remote user not found in /etc/passwd ($REMOTE_USER).";  elif [ "$OLD_UID" = "$NEW_UID" -a "$OLD_GID" = "$NEW_GID" ]; then   echo "UIDs and GIDs are the same ($NEW_UID:$NEW_GID).";  elif [ "$OLD_UID" != "$NEW_UID" -a -n "$EXISTING_USER" ]; then   echo "User with UID exists ($EXISTING_USER=$NEW_UID).";  elif [ "$OLD_GID" != "$NEW_GID" -a -n "$EXISTING_GROUP" ]; then   echo "Group with GID exists ($EXISTING_GROUP=$NEW_GID).";  else   echo "Updating UID:GID from $OLD_UID:$OLD_GID to $NEW_UID:$NEW_GID.";   sed -i -e "s/\(${REMOTE_USER}:[^:]*:\)[^:]*:[^:]*/\1${NEW_UID}:${NEW_GID}/" /etc/passwd;   if [ "$OLD_GID" != "$NEW_GID" ]; then    sed -i -e "s/\([^:]*:[^:]*:\)${OLD_GID}:/\1${NEW_GID}:/" /etc/group;   fi;   chown -R $NEW_UID:$NEW_GID $HOME_FOLDER;  fi; # buildkit
> SHELL [/bin/sh -c]
> ARG NEW_GID
> ARG NEW_UID
> ARG REMOTE_USER
> USER root

Conclusion

• The image ending in uid is switching to a non-root user and is taking extra measures to guarantee that the uid and guid are each 1000 (see the long RUN statement). It has a bunch of error handling to output an error if another user/group already exists at 1000.
• I'm guessing the devcontainer programmers are doing this because they can't be sure what base image is being used and thus USER vscode might not be at 1000/1000 for uid/guid.

Notes

• Details can vary by Linux distro (I think), but basically, if you guarantee your user ids/group ids are at 1000 or above you are in 'non-system user' (=regular user) uid space. Example discussion: https://ubuntuforums.org/showthread.php?t=1740376
• Some people recommend moving to 10000, not 1000, to have a lower probability of running into a pre-existing user at the 1000 range, which is quite likely, since the first non-system user will be at 1000, if no other steps are taken. Example discussion: https://news.ycombinator.com/item?id=25621610
• I'm not sure why the extra code doesn't first determine the first available uids/guids above 1000 and use those instead of 1000, just in case 1000 is already taken.