Try this way instead.

.gitea/workflows/build.yml

@@ -43,11 +43,5 @@ jobs:
           platforms: linux/amd64
           push: true
           tags: git.toast-server.net/toast/kon:main
-          cache-from: type=registry,ref=git.toast-server.net/toast/kon:main
-          cache-to: type=inline
-
-      - name: Save build cache
-        uses: actions/cache@704facf57e6136b1bc63b828d79edcd491f0ee84 # v3
-        with:
-          path: /tmp/.buildx-cache
-          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max