When clicking anywhere on the website to view public profile you get URL like this: example.com/profile/Username
It also uses caps and it looks quite bad if you ask me.
In oc-includes/osclass/helpers/hUsers.php
I replaced:
$path = osc_base_url(false, true) . osc_get_preference('rewrite_user_profile') . '/' . $user['s_username'];

With:

$path = osc_base_url(false, true) . osc_get_preference('rewrite_user_profile') . '/' . strtolower($user['s_username']);

Sufficient just to update username in backoffice.

Sufficient just to update username in backoffice.

For each and every user?

User itself should nit be able to define username. It should be autogenerated as slug.