failed to solve: failed to parse stage name "{RUN_MODE}":

[devcomputer]

Doesnt work for me:

# docker compose build
WARN[0000] /root/strapi-docker-starter/docker-compose.yml: `version` is obsolete 
[+] Building 0.6s (2/2) FINISHED                                                                                                                                                  docker:default
 => [frontend internal] load build definition from Dockerfile                                                                                                                               0.2s
 => => transferring dockerfile: 385B                                                                                                                                                        0.0s
 => [strapi internal] load build definition from Dockerfile                                                                                                                                 0.2s
 => => transferring dockerfile: 389B                                                                                                                                                        0.0s
failed to solve: failed to parse stage name "{RUN_MODE}": invalid reference format: repository name (library/{RUN_MODE}) must be lowercase
~/strapi-docker-starter #

[devcomputer]

so both Dockerfiles are not good.
server/Dockerfile
frontend/Dockerfile

Last line is:
FROM {RUN_MODE}

but needs to be
FROM ${RUN_MODE}