maybe

.gitea/actions/build/action.yml

@@ -32,16 +32,16 @@ runs:
 
     - name: Set repository variable
       shell: bash
+      id: repo
       run: |
         REPOSITORY=$(echo "${{ gitea.repository }}" | tr '[:upper:]' '[:lower:]')
-        echo "REPOSITORY=$REPOSITORY" >> $GITHUB_ENV
-        echo "Repository: $REPOSITORY"
+        echo "name=$REPOSITORY" >> $GITHUB_OUTPUT
 
     - name: Build and push image
       uses: docker/build-push-action@v6
       with:
         push: true
-        tags: '${{ vars.INSTANCE_URL }}/$REPOSITORY:${{ inputs.tag }}'
+        tags: '${{ vars.INSTANCE_URL }}/${{ steps.repo.outputs.name }}:${{ inputs.tag }}'
 
     - name: Set output
       shell: bash