diff --git a/frontend/app/player/web/TabManager.ts b/frontend/app/player/web/TabManager.ts
index b9af590b3..e6befcfb5 100644
--- a/frontend/app/player/web/TabManager.ts
+++ b/frontend/app/player/web/TabManager.ts
@@ -289,7 +289,6 @@ export default class TabSessionManager {
           );
         }
         break;
-      case MType.Fetch:
       case MType.NetworkRequest:
         this.lists.lists.fetch.insert(
           getResourceFromNetworkRequest(msg, this.sessionStart)
diff --git a/frontend/app/player/web/managers/DOM/DOMManager.ts b/frontend/app/player/web/managers/DOM/DOMManager.ts
index 057379b90..9a596ec80 100644
--- a/frontend/app/player/web/managers/DOM/DOMManager.ts
+++ b/frontend/app/player/web/managers/DOM/DOMManager.ts
@@ -408,38 +408,6 @@ export default class DOMManager extends ListWalker<Message> {
         vText.setData(msg.data);
         return;
       }
-
-      /** @deprecated
-       * since 4.0.2 in favor of AdoptedSsInsertRule/DeleteRule + AdoptedSsAddOwner as a common case for StyleSheets
-       */
-      case MType.CssInsertRule: {
-        let styleSheet = this.olStyleSheetsDeprecated.get(msg.id);
-        if (!styleSheet) {
-          const vElem = this.vElements.get(msg.id);
-          if (!vElem) {
-            logger.error('CssInsertRule: Node not found', msg);
-            return;
-          }
-          if (!isStyleVElement(vElem)) {
-            logger.error('CssInsertRule: Non-style element', msg);
-            return;
-          }
-          styleSheet = OnloadStyleSheet.fromStyleElement(vElem.node);
-          this.olStyleSheetsDeprecated.set(msg.id, styleSheet);
-        }
-        styleSheet.insertRule(msg.rule, msg.index);
-        return;
-      }
-      case MType.CssDeleteRule: {
-        const styleSheet = this.olStyleSheetsDeprecated.get(msg.id);
-        if (!styleSheet) {
-          logger.error('CssDeleteRule: StyleSheet was not created', msg);
-          return;
-        }
-        styleSheet.deleteRule(msg.index);
-        return;
-      }
-      /* end @deprecated */
       case MType.CreateIFrameDocument: {
         const vElem = this.vElements.get(msg.frameID);
         if (!vElem) {
diff --git a/frontend/app/player/web/messages/rewriter/rewriteMessage.ts b/frontend/app/player/web/messages/rewriter/rewriteMessage.ts
index b64817e64..535a8a28c 100644
--- a/frontend/app/player/web/messages/rewriter/rewriteMessage.ts
+++ b/frontend/app/player/web/messages/rewriter/rewriteMessage.ts
@@ -4,8 +4,6 @@ import type {
   RawSetNodeAttribute,
   RawSetCssDataURLBased,
   RawSetCssData,
-  RawCssInsertRuleURLBased,
-  RawCssInsertRule,
   RawAdoptedSsInsertRuleURLBased,
   RawAdoptedSsInsertRule,
   RawAdoptedSsReplaceURLBased,
@@ -57,12 +55,6 @@ const REWRITERS = {
     data: rewriteCSS(msg.baseURL, msg.data),
     tp: MType.SetCssData,
   }),
-  [MType.CssInsertRuleURLBased]: (msg: RawCssInsertRuleURLBased): RawCssInsertRule =>
-  ({
-    ...msg,
-    rule: rewriteCSS(msg.baseURL, msg.rule),
-    tp: MType.CssInsertRule,
-  }),
   [MType.AdoptedSsInsertRuleURLBased]: (msg: RawAdoptedSsInsertRuleURLBased): RawAdoptedSsInsertRule =>
   ({
     ...msg,