--- a/mail/app/profile/all-thunderbird.js
+++ b/mail/app/profile/all-thunderbird.js
@@ -850,18 +850,16 @@ pref("devtools.inspector.imagePreviewToo
 // Enable user agent style inspection in rule-view
 pref("devtools.inspector.showUserAgentStyles", false);
 // Show native anonymous content and user agent shadow roots
 pref("devtools.inspector.showAllAnonymousContent", false);
 // Enable the new Rules View
 pref("devtools.inspector.new-rulesview.enabled", false);
 // Enable the compatibility tool in the inspector.
 pref("devtools.inspector.compatibility.enabled", false);
-// Enable the new Box Model Highlighter with renderer in parent process
-pref("devtools.inspector.use-new-box-model-highlighter", false);
 // Enable color scheme simulation in the inspector.
 pref("devtools.inspector.color-scheme-simulation.enabled", false);
 
 // Grid highlighter preferences
 pref("devtools.gridinspector.gridOutlineMaxColumns", 50);
 pref("devtools.gridinspector.gridOutlineMaxRows", 50);
 pref("devtools.gridinspector.showGridAreas", false);
 pref("devtools.gridinspector.showGridLineNumbers", false);