Branch strategy is typically 11.0.x or 11.1.x instead of 11.x-1.x
Then under module homepage administer releases and create a 11.0.x-dev release. This then shows as a dev/contribution release in the version/target for MRs while the tagged releases still remain the primary release, e.g. how it says 'Development release' here:
https://www.drupal.org/project/footnotes →
Finally, within gitlab, please under repository set the default branch to the 11.0.x branch to match