Pauthauto breaking for one specific page
The redirect issue described here is pretty common for sites where the Redirect module (drupal.org/project/redirect) is enabled. The module has a default config setting that creates a redirect anytime the url on the node is edited (this includes through bulk operations such as a pathauto alias generation process). 

This setting can lead to the infinite redirect issue when a user changes an alias and then changes it back, resulting in a circular reference/infinite redirect.

I highly recommend disabling this setting for sites under construction (where urls are in flux) and enabling once deployed to production.  You can toggle it at /admin/config/search/redirect/settings (it's the very first setting on the page, shown in the partial screenshot below)



For production sites, be wary of changing a url multiple times- check/manage the list of redirects associated with the node on the node edit form as shown below



You can also check/manage redirects from the full list of redirects assigned in Drupal at /admin/config/search/redirect