diff --git a/sliding-sync/default.nix b/sliding-sync/default.nix
index abd5fe2..04efed3 100644
--- a/sliding-sync/default.nix
+++ b/sliding-sync/default.nix
@@ -84,6 +84,15 @@ in
   };
 
   config = lib.mkIf cfg.enable {
+    warnings = lib.optionals config.services.matrix-synapse-next.enable [
+      ''
+        services.matrix-synapse.sliding-sync is no longer necessary to use sliding-sync with synapse,
+        and the extra module will be removed from `nixos-matrix-modules` in the future.
+        If you are only using this service via `nixos-matrix-modules` you can safely remove options like
+        `services.matrix-synapse.sliding-sync.environmentFile`.
+      ''
+    ];
+
     services.postgresql = lib.optionalAttrs cfg.createDatabase {
       enable = true;
       ensureDatabases = [ "matrix-sliding-sync" ];
diff --git a/synapse-module/default.nix b/synapse-module/default.nix
index a523bb0..7ff7e45 100644
--- a/synapse-module/default.nix
+++ b/synapse-module/default.nix
@@ -395,6 +395,9 @@ in
         message = "Some listeners are missing either a socket path or a bind_address + port to listen on";
       }) cfg.settings.listeners);
 
+    warnings = [ ] ++ lib.optional cfg.enableSlidingSync
+      "the option services.matrix-synapse-next.enableSlidingSync no longer has any effect (and is enabled by default)";
+
     users.users.matrix-synapse = {
       group = "matrix-synapse";
       home = cfg.dataDir;
@@ -452,19 +455,5 @@ in
         };
       };
     };
-
-    services.matrix-synapse-next.settings.extra_well_known_client_content."org.matrix.msc3575.proxy" = mkIf cfg.enableSlidingSync {
-      url = "https://${config.services.matrix-synapse.sliding-sync.publicBaseUrl}";
-    };
-    services.matrix-synapse.sliding-sync = mkIf cfg.enableSlidingSync {
-      enable = true;
-      enableNginx = lib.mkDefault cfg.enableNginx;
-      publicBaseUrl = lib.mkDefault "slidingsync.${cfg.settings.server_name}";
-
-      settings = {
-        SYNCV3_SERVER = lib.mkDefault "https://${cfg.public_baseurl}";
-        SYNCV3_PROM = lib.mkIf cfg.settings.enable_metrics (lib.mkDefault "127.0.0.1:9001");
-      };
-    };
   };
 }