we have solved the problem by upgrading from Debian 9 to Debian 10... Somehow this solved all the problem, we did not change anything, everything else stayed the same version (node/npm/NodeBB)... FYI...
Please be careful and take extra caution while installing this plugin nodebb-plugin-sso-auth0. It seems plugin is broken
The developer appears to be active. You should open a new issue on their github if you are having problems.