In 99.9% of these cases you have the following problem:
You have set up a $live_site in configuration.php with a URL like https://www.example.com but also set up a redirection in .htaccess maker from www to non-www (or vice versa). This creates a redirection loop because the .htaccess will redirect www.example.com to example.com and Joomla's $live_site will redirect example.com back to www.example.com. You are warned about this in the .htaccess Maker.
Another issue might be that $live_site is set to use http:// but you have enabled HSTS in the .htaccess Maker. Again, the .htaccess will redirect http:// to https:// and Joomla will redirect https:// to http:// because of the $live_site.
In all cases the correct solution is to edit configuration.php and set
$live_site = '';
You DO NOT need a non-empty $live_site. This is a remnant for some very old, very weirdly configured hosts which would not set the HOST environment variable. These were rare 17 years ago, you'd be hard pressed to find any of them still around in 2022. Therefore you do not need the $live_site.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!