diff --git a/api/Element.json b/api/Element.json
index e0bcbd11e5a03f..d1474889cd249d 100644
--- a/api/Element.json
+++ b/api/Element.json
@@ -5929,6 +5929,47 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "escapes_lt_gt_in_attributes": {
+          "__compat": {
+            "description": "Serializes `<` and `>` in attributes as `&amp;lt;` and `&amp;gt;` (see [this spec issue](https://github.com/whatwg/html/issues/6235))",
+            "support": {
+              "chrome": {
+                "version_added": "114",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "enable-experimental-web-platform-features",
+                    "value_to_set": "enabled"
+                  }
+                ]
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": "preview"
+              },
+              "firefox_android": "mirror",
+              "ie": {
+                "version_added": false
+              },
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": "preview"
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": false,
+              "deprecated": false
+            }
+          }
         }
       },
       "gotpointercapture_event": {
@@ -6291,6 +6332,47 @@
               "deprecated": false
             }
           }
+        },
+        "escapes_lt_gt_in_attributes": {
+          "__compat": {
+            "description": "Serializes `<` and `>` in attributes as `&amp;lt;` and `&amp;gt;` (see [this spec issue](https://github.com/whatwg/html/issues/6235))",
+            "support": {
+              "chrome": {
+                "version_added": "114",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "enable-experimental-web-platform-features",
+                    "value_to_set": "enabled"
+                  }
+                ]
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": "preview"
+              },
+              "firefox_android": "mirror",
+              "ie": {
+                "version_added": false
+              },
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": "preview"
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": false,
+              "deprecated": false
+            }
+          }
         }
       },
       "input_event": {
@@ -7468,6 +7550,47 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "escapes_lt_gt_in_attributes": {
+          "__compat": {
+            "description": "Serializes `<` and `>` in attributes as `&amp;lt;` and `&amp;gt;` (see [this spec issue](https://github.com/whatwg/html/issues/6235))",
+            "support": {
+              "chrome": {
+                "version_added": "114",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "enable-experimental-web-platform-features",
+                    "value_to_set": "enabled"
+                  }
+                ]
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": "preview"
+              },
+              "firefox_android": "mirror",
+              "ie": {
+                "version_added": false
+              },
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": "preview"
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": false,
+              "deprecated": false
+            }
+          }
         }
       },
       "part": {
diff --git a/api/ShadowRoot.json b/api/ShadowRoot.json
index eecf9ff90962fe..297dae03f6e6f9 100644
--- a/api/ShadowRoot.json
+++ b/api/ShadowRoot.json
@@ -391,6 +391,40 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "escapes_lt_gt_in_attributes": {
+          "__compat": {
+            "description": "Serializes `<` and `>` in attributes as `&amp;lt;` and `&amp;gt;` (see [this spec issue](https://github.com/whatwg/html/issues/6235))",
+            "support": {
+              "chrome": {
+                "version_added": false
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": "preview"
+              },
+              "firefox_android": "mirror",
+              "ie": {
+                "version_added": false
+              },
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": "preview"
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": false,
+              "deprecated": false
+            }
+          }
         }
       },
       "getSelection": {
@@ -542,6 +576,47 @@
               "deprecated": false
             }
           }
+        },
+        "escapes_lt_gt_in_attributes": {
+          "__compat": {
+            "description": "Serializes `<` and `>` in attributes as `&amp;lt;` and `&amp;gt;` (see [this spec issue](https://github.com/whatwg/html/issues/6235))",
+            "support": {
+              "chrome": {
+                "version_added": "114",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "enable-experimental-web-platform-features",
+                    "value_to_set": "enabled"
+                  }
+                ]
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": "preview"
+              },
+              "firefox_android": "mirror",
+              "ie": {
+                "version_added": false
+              },
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": "preview"
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": false,
+              "deprecated": false
+            }
+          }
         }
       },
       "mode": {