If image exists already, docker-compose tries to find tag ":true" and fails

If my images “test-image:latest” and “test-image:6.0.0” exist already, then docker-compose fails with:
manifest for test-image:true not found: manifest unknown: manifest unknown

So, it tries to find the image with the tag “true”. If I delete the images, then it will download it, if found in docker hub. Why does it change the tag to “true”?

I’m trying to build a pipeline for Gitlab CI to build images and then upload them. So this error happens in Gitlab under docker/compose:latest…