per https://wordpress.org/support/topic/installed-after-gravity-forms-seeing-undefined-index-as-field-values/

So within the ‘Email Sender’ input I found;
<br /><b>Notice</b>: Undefined index: sender in <b>/home/eaglehursthomes/public_html/wp-content/plugins/forms-3rdparty-integration/plugin-ui.php</b> on line <b>69</b><br />

and

then went to open the ‘Service 1’ default service’s accordion where I found the ‘Failure Message (Mask)’ field had the following content;

<br />
<b>Notice</b>:  Undefined index: failure in <b>/home/eaglehursthomes/public_html/wp-content/plugins/forms-3rdparty-integration/plugin-ui.php</b> on line <b>151</b><br />

Non-critical