Clicking Checkbox Fails on 5.7.1 (multisite)

[jeffmikels]

On Wordpress 5.7.1 (multisite)

When clicking the checkbox on a post page, the following request is sent to the wordpress admin-ajax.php endpoint:

HEADERS

:authority: lafayettecc.org
:method: POST
:path: /blogs/jeff/wp-admin/admin-ajax.php
:scheme: https
accept: */*
accept-encoding: gzip, deflate, br
accept-language: en-US,en;q=0.9,fr;q=0.8
cache-control: no-cache
content-length: 75
content-type: application/x-www-form-urlencoded; charset=UTF-8

BODY

_ajax_nonce: 475125b461
checked: true
post_ID: 2504
action: public-post-preview

And this is the response:

HEADERS

access-control-allow-credentials: true
access-control-allow-origin: https://lafayettecc.org
cache-control: no-cache, must-revalidate, max-age=0
content-type: text/html; charset=UTF-8
date: Tue, 27 Jul 2021 20:27:27 GMT
expires: Wed, 11 Jan 1984 05:00:00 GMT
referrer-policy: strict-origin-when-cross-origin
server: nginx/1.14.0 (Ubuntu)
x-content-type-options: nosniff
x-frame-options: SAMEORIGIN
x-robots-tag: noindex

BODY

0

However, for some reason, when executing the exact command from CURL (including all headers and cookies of course) it succeeds

[ocean90]

I wasn't able to reproduce it and there are no further reports so I suspect the reason is/was some page caching issues.