This issue appears to be a duplicate of this issue. I don't think this one is similar since Ahmad reported he was not using enrol_ldap whereas you are, and disabling it stops the problem.
enrol_ldap outputs messages to the error log but also includes non-error informational messages. So that message could just be a user being enrolled normally. But… the string is wrong!
The default language string (enrol/ldap/lang/en/enrol_ldap.php line 72) is:
Enrol user '{username}' into course '{shortname}' (id {course_id})
but yours is:
Register user \ xc3 \ xa1rio' 111201 'in the course' TAG-AR001- ARTS - T11 - 2020/1 '(id 944)
Has the enrol_ldap plugin been modified on your site? Or could the language strings have been changed?
I suggest:
- Searching the Moodle source code for that string. Either search enrol/ldap/lang/en/enrol_ldap.php or run command grep -rnE "Register user.+in the course" * from the Moodle source code folder.
- Finding the PHP-FPM logs. The Apache error log captures messages from PHP-FPM but these can get truncated.