As per ticket #36400 I installed Admin Tools on a test Joomla 4 site and then created a default .htaccess file. This blocked access to the site with ERR_TOO_MANY_REDIRECTS, so I deleted the file and could then get access to the back end site. Although strangely the front end is still not visible using Chrome, Firefox or Vivaldi browsers.
I've gone through the .htaccess options, switching them off and then back on but it still blocks the site with the same error message.
I've attached the default htaccess file