--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -2666,43 +2666,16 @@ AppendCSPFromHeader(nsIContentSecurityPo
         MOZ_LOG(gCspPRLog, LogLevel::Debug,
                 ("CSP refined with policy: \"%s\"",
                 NS_ConvertUTF16toUTF8(policy).get()));
       }
   }
   return NS_OK;
 }
 
-bool
-nsDocument::IsLoopDocument(nsIChannel *aChannel)
-{
-  nsCOMPtr<nsIURI> chanURI;
-  nsresult rv = aChannel->GetOriginalURI(getter_AddRefs(chanURI));
-  NS_ENSURE_SUCCESS(rv, false);
-
-  bool isAbout = false;
-  bool isLoop = false;
-  rv = chanURI->SchemeIs("about", &isAbout);
-  NS_ENSURE_SUCCESS(rv, false);
-  if (isAbout) {
-    nsCOMPtr<nsIURI> loopURI;
-    rv = NS_NewURI(getter_AddRefs(loopURI), "about:loopconversation");
-    NS_ENSURE_SUCCESS(rv, false);
-    rv = chanURI->EqualsExceptRef(loopURI, &isLoop);
-    NS_ENSURE_SUCCESS(rv, false);
-    if (!isLoop) {
-      rv = NS_NewURI(getter_AddRefs(loopURI), "about:looppanel");
-      NS_ENSURE_SUCCESS(rv, false);
-      rv = chanURI->EqualsExceptRef(loopURI, &isLoop);
-      NS_ENSURE_SUCCESS(rv, false);
-    }
-  }
-  return isLoop;
-}
-
 void
 nsDocument::ApplySettingsFromCSP(bool aSpeculative)
 {
   nsresult rv = NS_OK;
   if (!aSpeculative) {
     // 1) apply settings from regular CSP
     nsCOMPtr<nsIContentSecurityPolicy> csp;
     rv = NodePrincipal()->GetCsp(getter_AddRefs(csp));
@@ -2815,31 +2788,27 @@ nsDocument::InitCSP(nsIChannel* aChannel
     }
   }
 
   // Check if this is a document from a WebExtension.
   nsString addonId;
   principal->GetAddonId(addonId);
   bool applyAddonCSP = !addonId.IsEmpty();
 
-  // Check if this is part of the Loop/Hello service
-  bool applyLoopCSP = IsLoopDocument(aChannel);
-
   // Check if this is a signed content to apply default CSP.
   bool applySignedContentCSP = false;
   nsCOMPtr<nsILoadInfo> loadInfo = aChannel->GetLoadInfo();
   if (loadInfo && loadInfo->GetVerifySignedContent()) {
     applySignedContentCSP = true;
   }
 
   // If there's no CSP to apply, go ahead and return early
   if (!applyAppDefaultCSP &&
       !applyAppManifestCSP &&
       !applyAddonCSP &&
-      !applyLoopCSP &&
       !applySignedContentCSP &&
       cspHeaderValue.IsEmpty() &&
       cspROHeaderValue.IsEmpty()) {
     if (MOZ_LOG_TEST(gCspPRLog, LogLevel::Debug)) {
       nsCOMPtr<nsIURI> chanURI;
       aChannel->GetURI(getter_AddRefs(chanURI));
       nsAutoCString aspec;
       chanURI->GetAsciiSpec(aspec);
@@ -2913,27 +2882,16 @@ nsDocument::InitCSP(nsIChannel* aChannel
   // Note that when the content signing becomes a standard, we might have
   // to restrict this enforcement to "remote content" only.
   if (applySignedContentCSP) {
     nsAdoptingString signedContentCSP =
       Preferences::GetString("security.signed_content.CSP.default");
     csp->AppendPolicy(signedContentCSP, false, false);
   }
 
-  // ----- if the doc is part of Loop, apply the loop CSP
-  if (applyLoopCSP) {
-    nsAdoptingString loopCSP;
-    loopCSP = Preferences::GetString("loop.CSP");
-    NS_ASSERTION(loopCSP, "Missing loop.CSP preference");
-    // If the pref has been removed, we continue without setting a CSP
-    if (loopCSP) {
-      csp->AppendPolicy(loopCSP, false, false);
-    }
-  }
-
   // ----- if there's a full-strength CSP header, apply it.
   if (!cspHeaderValue.IsEmpty()) {
     rv = AppendCSPFromHeader(csp, cspHeaderValue, false);
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
   // ----- if there's a report-only CSP header, apply it.
   if (!cspROHeaderValue.IsEmpty()) {

--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -1719,17 +1719,16 @@ private:
   mozilla::dom::VisibilityState GetVisibilityState() const;
   void NotifyStyleSheetAdded(mozilla::StyleSheetHandle aSheet, bool aDocumentSheet);
   void NotifyStyleSheetRemoved(mozilla::StyleSheetHandle aSheet, bool aDocumentSheet);
 
   void PostUnblockOnloadEvent();
   void DoUnblockOnload();
 
   nsresult CheckFrameOptions();
-  bool IsLoopDocument(nsIChannel* aChannel);
   nsresult InitCSP(nsIChannel* aChannel);
 
   /**
    * Find the (non-anonymous) content in this document for aFrame. It will
    * be aFrame's content node if that content is in this document and not
    * anonymous. Otherwise, when aFrame is in a subdocument, we use the frame
    * element containing the subdocument containing aFrame, and/or find the
    * nearest non-anonymous ancestor in this document.