make old theme tab truly deprecated

src/components/settings_modal/settings_modal_user_content.js

@@ -64,6 +64,9 @@ const SettingsModalContent = {
     },
     bodyLock () {
       return this.$store.state.interface.settingsModalState === 'visible'
+    },
+    expertLevel () {
+      return this.$store.state.config.expertLevel
     }
   },
   methods: {

src/components/settings_modal/settings_modal_user_content.vue

@@ -28,7 +28,8 @@
       <StyleTab />
     </div>
     <div
-      :label="$t('settings.theme')"
+      v-if="expertLevel > 0"
+      :label="$t('settings.theme_old')"
       icon="paint-brush"
       data-tab-name="theme"
     >