For #17086 #17143: Temporarily turn off Nimbus

app/src/androidTest/java/org/mozilla/fenix/ui/robots/SettingsSubMenuDataCollectionRobot.kt

@@ -38,7 +38,9 @@ class SettingsSubMenuDataCollectionRobot {
         verifyDataCollectionOptions()
         verifyUsageAndTechnicalDataSwitchDefault()
         verifyMarketingDataSwitchDefault()
-        verifyExperimentsSwitchDefault()
+        // Temporarily disabled until https://github.com/mozilla-mobile/fenix/issues/17086 and
+        // https://github.com/mozilla-mobile/fenix/issues/17143 are resolved:
+        // verifyExperimentsSwitchDefault()
     }
 
     class Transition {
@@ -80,8 +82,10 @@ private fun assertDataCollectionOptions() {
     onView(withText(marketingDataText))
         .check(matches(withEffectiveVisibility(Visibility.VISIBLE)))
 
-    onView(withText(R.string.preference_experiments_2)).check(matches(withEffectiveVisibility(Visibility.VISIBLE)))
-    onView(withText(R.string.preference_experiments_summary_2)).check(matches(withEffectiveVisibility(Visibility.VISIBLE)))
+    // Temporarily disabled until https://github.com/mozilla-mobile/fenix/issues/17086 and
+    // https://github.com/mozilla-mobile/fenix/issues/17143 are resolved:
+    // onView(withText(R.string.preference_experiments_2)).check(matches(withEffectiveVisibility(Visibility.VISIBLE)))
+    // onView(withText(R.string.preference_experiments_summary_2)).check(matches(withEffectiveVisibility(Visibility.VISIBLE)))
 }
 
 private fun usageAndTechnicalDataButton() = onView(withText(R.string.preference_usage_data))

app/src/main/java/org/mozilla/fenix/FeatureFlags.kt

@@ -35,7 +35,14 @@ object FeatureFlags {
      * Enables the Nimbus experiments library, especially the settings toggle to opt-out of
      * all experiments.
      */
-    val nimbusExperiments = Config.channel.isNightlyOrDebug
+    // IMPORTANT: Only turn this back on once the following issues are resolved:
+    // - https://github.com/mozilla-mobile/fenix/issues/17086: Calls to
+    // getExperimentBranch seem to block on updateExperiments causing a
+    // large performance regression loading the home screen.
+    // - https://github.com/mozilla-mobile/fenix/issues/17143: Despite
+    // having wrapped getExperimentBranch/withExperiments in a catch-all
+    // users are still experiencing crashes.
+    const val nimbusExperiments = false
 
     /**
      * Enables the new MediaSession API.