Google Search Console – Submitted URL blocked due to other 4xx issue

I have also recently encountered this error for a page that was previously indexing just fine. It is not necessarily a page I need to be searchable but I don’t like to see errors in my coverage so want to resolve it. i looked through you previous ticket with a similar issues

the URL in question is
https://stellardiscovery.com/contact/

it checks out on the https://httpstatus.io/

I have entered my sitemap into search console but there doesn’t seem to be one in my robots.txt, should there be?

my robot.txt is as follows:

User-agent: *
Disallow: /calendar/action~posterboard/
Disallow: /calendar/action~agenda/
Disallow: /calendar/action~oneday/
Disallow: /calendar/action~month/
Disallow: /calendar/action~week/
Disallow: /calendar/action~stream/
Disallow: /calendar/action~undefined/
Disallow: /calendar/action~http:/
Disallow: /calendar/action~default/
Disallow: /calendar/action~poster/
Disallow: /calendar/action~*/
Disallow: /*controller=ai1ec_exporter_controller*
Disallow: /*/action~*/
Disallow: /astronomical-events/action~posterboard/
Disallow: /astronomical-events/action~agenda/
Disallow: /astronomical-events/action~oneday/
Disallow: /astronomical-events/action~month/
Disallow: /astronomical-events/action~week/
Disallow: /astronomical-events/action~stream/
Disallow: /astronomical-events/action~undefined/
Disallow: /astronomical-events/action~http:/
Disallow: /astronomical-events/action~default/
Disallow: /astronomical-events/action~poster/
Disallow: /astronomical-events/action~*/

I am not sure if one of the disallow lines would be stopping (or if these are actually needed as I think they are leftover from a plugin I no longer use). or if I should have some allow clauses. It is not really something I am familiar with so any assistance is appreciated.