I finally found a little hack that works for me :
FROM camunda/camunda-bpm-platform:run-7.14.0
COPY --chown=camunda:camunda camunda-cockpit-plugins/* /camunda/META-INF/resources/webjars/camunda/app/cockpit/scripts/
USER root
RUN apk add --no-cache zip
RUN zip -r internal/webapps/camunda-webapp-webjar-7.14.0.jar META-INF
USER camunda