try with newlinw

.github/workflows/trial.yml

@@ -4,7 +4,7 @@ on:
   workflow_dispatch:
   push:
   # schedule:
-  #   - cron: 0 3 * * 1
+  #   - cron: "0 3 * * 1"
   # push:
   #   tags:
   #     - "v*.*.*"
@@ -60,7 +60,7 @@ jobs:
             cupcakearmy/static
             ghcr.io/${{ github.repository }}
           tags: ${{ matrix.tags }}
-          sep-tags: ","
+          # sep-tags: ","
 
       - name: Build and push
         id: docker_build

tags/index.js

@@ -24,7 +24,7 @@ function convert(version, additional = []) {
   return {
     version,
     // https://github.com/docker/metadata-action#typeraw
-    tags: [version, ...additional].join(','),
+    tags: [version, ...additional].join('\n'),
   }
 }