I detected the loops after opening the product page in the Vivaldi browser. Edge, Chrome and Firefox did not have a problem with that.
The loop is related to the vmkeepalive.js file. The problem disappears after clearing the contents of this file.
The webshop now works normally. No errors in scripts. What is this file for?
VM 3.2.14
Joomla! 3.8.6
T3 Framework 2.7.0
PHP (fpm-fcgi) 7.2.4
It seems that the browser do not set the language in session.
Have you disabled the session ?
After the last update of the Vivaldi browser to version 1.15, this problem does not exist. :)