Error message on contribution: too many redirects
I was having the same issue and stumbled upon an answer to a very similar problem, although it didn't appear to be random like mine and yours. This is a pretty old issue, so not sure if my "answer" helps. All I did was navigate to CiviCRM >> Administer >> CiviContribute >> CiviContribute Component Settings. Set 'Default invoice payment page' field to the contribution page that was causing the "too many redirects" when we pressed Confirm. It was previously pointing to a contribution page associated with an expired campaign, which doesn't explain at all why the redirects error appeared to be random. We are running Wordpress 5.2.3 and CiviCRM 5.12.4.