diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index 884f8a41..1b53486b 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -2,8 +2,6 @@ name: Pull Requests
 
 on:
   pull_request:
-    branches:
-      - main # Only `main` base branch, because `2.1.x` has another build logic
 
 concurrency:
   # Only run once for latest commit per ref and cancel other (previous) runs.
@@ -75,6 +73,7 @@ jobs:
         run: sbt doc
 
   tests:
+    if: ${{ github.base_ref != '2.1.x' }}
     runs-on: ubuntu-20.04
     needs: # Waiting more lightweight checks
       - "check-code-style"
@@ -104,3 +103,35 @@ jobs:
         run: sbt ++$SCALA_VERSION 'testOnly -- xonly timefactor 5'
         env:
           SCALA_VERSION: ${{ matrix.scala }}
+
+  tests-21x:
+    if: ${{ github.base_ref == '2.1.x' }}
+    runs-on: ubuntu-20.04
+    needs: # Waiting more lightweight checks
+      - "check-code-style"
+      - "check-binary-compatibility"
+      - "check-docs"
+    strategy:
+      matrix:
+        jdk: [ 11, 8 ]
+        scala: [ 2.12.15, 2.13.8 ] # Should be sync with Mergify conditions (.mergify.yml)
+    name: Check / Tests (Scala ${{ matrix.scala }} & JDK ${{ matrix.jdk }})
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          # we don't know what commit the last tag was it's safer to get entire repo so previousStableVersion resolves
+          fetch-depth: 0
+
+      - name: Set up JDK ${{ matrix.jdk }}
+        uses: olafurpg/setup-scala@v13
+        with:
+          java-version: adopt@1.${{ matrix.jdk }}
+
+      - name: Cache Coursier cache
+        uses: coursier/cache-action@v6.2
+
+      - name: Tests
+        run: sbt ++$SCALA_VERSION 'testOnly -- xonly timefactor 5'
+        env:
+          SCALA_VERSION: ${{ matrix.scala }}
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 5668bc2f..03d126e1 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -4,7 +4,9 @@ on:
   push:
     branches: # Snapshots
       - main
+#      - 2.1.x # TODO: 2.1.x don't support sbt-ci-release yet
     tags: ["*"] # Releases
+    tags-ignore: [ "2.1.*" ] # TODO: 2.1.x don't support sbt-ci-release yet
 
 jobs:
   publish-artifacts:
diff --git a/.mergify.yml b/.mergify.yml
index d6d97843..586e48d5 100644
--- a/.mergify.yml
+++ b/.mergify.yml
@@ -7,11 +7,30 @@ queue_rules:
       - check-success=Check / Docs
       - check-success~=^Check / Tests \(Scala 2\.13\.(\d+) & JDK 11\)$
       - check-success~=^Check / Tests \(Scala 2\.13\.(\d+) & JDK 8\)$
+  - name: 2-1-x
+    conditions:
+      # Conditions to get out of the queue (= merged)
+      - check-success=Check / Code Style
+      - check-success=Check / Binary Compatibility
+      - check-success=Check / Docs
+      - check-success~=^Check / Tests \(Scala 2\.12\.(\d+) & JDK 11\)$
+      - check-success~=^Check / Tests \(Scala 2\.12\.(\d+) & JDK 8\)$
+      - check-success~=^Check / Tests \(Scala 2\.13\.(\d+) & JDK 11\)$
+      - check-success~=^Check / Tests \(Scala 2\.13\.(\d+) & JDK 8\)$
+
 
 pull_request_rules:
-  - name: Merge PRs that are ready
+  - name: Merge PRs for 2.1.x branch that are ready
     conditions:
+      - base==2.1.x
       - status-success=Travis CI - Pull Request
+      - check-success=Check / Code Style
+      - check-success=Check / Binary Compatibility
+      - check-success=Check / Docs
+      - check-success~=^Check / Tests \(Scala 2\.12\.(\d+) & JDK 11\)$
+      - check-success~=^Check / Tests \(Scala 2\.12\.(\d+) & JDK 8\)$
+      - check-success~=^Check / Tests \(Scala 2\.13\.(\d+) & JDK 11\)$
+      - check-success~=^Check / Tests \(Scala 2\.13\.(\d+) & JDK 8\)$
       - status-success=typesafe-cla-validator
       - "#approved-reviews-by>=1"
       - "#review-requested=0"
@@ -19,12 +38,13 @@ pull_request_rules:
       - label!=status:block-merge
       - label=status:merge-when-green
     actions:
-      merge:
+      queue:
         method: merge
+        name: 2-1-x
 
-  - name: Merge PRs for main branch that are ready
+  - name: Merge PRs (except 2.1.x branch) that are ready
     conditions:
-      - base=main # TODO: remove this line and rule above after stable release 2.2.x
+      - base!=2.1.x
       - status-success=Travis CI - Pull Request
       - check-success=Check / Code Style
       - check-success=Check / Binary Compatibility