magento-commerce/magento2-login-as-customer#158: Enable Page Cache - Admin is not logged in as customer because was redirected to the "Sign In" page.

Author: engcom-Foxtrot

app/code/Magento/LoginAsCustomerFrontendUi/view/frontend/layout/loginascustomer_login_index.xml

@@ -13,7 +13,7 @@
             </action>
         </referenceBlock>
         <referenceContainer name="content">
-            <block class="Magento\Framework\View\Element\Template" name="loginascustomer_login" template="Magento_LoginAsCustomerFrontendUi::login.phtml"/>
+            <block class="Magento\Framework\View\Element\Template" name="loginascustomer_login" template="Magento_LoginAsCustomerFrontendUi::login.phtml" cacheable="false"/>
         </referenceContainer>
     </body>
 </page>