php putenv restrictions on server environment, how does this affect civicrm
It might if you use something other than US english, or whatever your host has set for the system-level.

See https://github.com/civicrm/civicrm-core/blob/master/CRM/Core/I18n.php

But it will probably still work anyway because CiviCRM sets other variables too that have higher priority. See
https://www.gnu.org/software/gettext/manual/html_node/Locale-Environment-Variables.html