Error 500 wp-admin

Hello. I have a client and yesterday sent me an email telling me that can not access to the wordpress dashboard. So I was searching for solutions and found some topics with this problem.
I already deactivate the plugins, rename the theme folder and rename the .htaccess file but nothing changed.

From the log file of the root folder I get this message:

[18-Jan-2023 14:16:52 UTC] PHP Warning:  Illegal string offset 'remember' in /home/apoturperu/public_html/wp-includes/user.php on line 41
[18-Jan-2023 14:16:52 UTC] PHP Warning:  Cannot assign an empty string to a string offset in /home/apoturperu/public_html/wp-includes/user.php on line 41
[18-Jan-2023 14:16:52 UTC] PHP Warning:  Illegal string offset 'user_login' in /home/apoturperu/public_html/wp-includes/user.php on line 56
[18-Jan-2023 14:16:52 UTC] PHP Fatal error:  Uncaught Error: Cannot create references to/from string offsets in /home/apoturperu/public_html/wp-includes/user.php:56
Stack trace:
#0 /home/apoturperu/public_html/wp-login.php(806): wp_signon('', '')
#1 {main}
  thrown in /home/apoturperu/public_html/wp-includes/user.php on line 56

I activate the debugger and get this message:

[18-Jan-2023 14:42:17 UTC] PHP Deprecated:  Function get_magic_quotes_gpc() is deprecated in /home/apoturperu/public_html/wp-includes/load.php on line 583
[18-Jan-2023 14:42:17 UTC] PHP Deprecated:  Function create_function() is deprecated in /home/apoturperu/public_html/wp-includes/pomo/translations.php on line 208
[18-Jan-2023 14:42:51 UTC] PHP Deprecated:  Function get_magic_quotes_gpc() is deprecated in /home/apoturperu/public_html/wp-includes/load.php on line 583
[18-Jan-2023 14:42:51 UTC] PHP Deprecated:  Function create_function() is deprecated in /home/apoturperu/public_html/wp-includes/pomo/translations.php on line 208
[18-Jan-2023 14:42:51 UTC] PHP Deprecated:  Function create_function() is deprecated in /home/apoturperu/public_html/wp-includes/pomo/translations.php on line 208
[18-Jan-2023 14:42:51 UTC] PHP Deprecated:  Function get_magic_quotes_gpc() is deprecated in /home/apoturperu/public_html/wp-includes/formatting.php on line 3785
[18-Jan-2023 14:42:51 UTC] PHP Deprecated:  Function get_magic_quotes_gpc() is deprecated in /home/apoturperu/public_html/wp-includes/formatting.php on line 3785
[18-Jan-2023 14:42:51 UTC] PHP Deprecated:  Function get_magic_quotes_gpc() is deprecated in /home/apoturperu/public_html/wp-includes/load.php on line 583
[18-Jan-2023 14:42:51 UTC] PHP Deprecated:  Function create_function() is deprecated in /home/apoturperu/public_html/wp-includes/pomo/translations.php on line 208
[18-Jan-2023 14:42:51 UTC] PHP Warning:  Illegal string offset 'remember' in /home/apoturperu/public_html/wp-includes/user.php on line 41
[18-Jan-2023 14:42:51 UTC] PHP Warning:  Cannot assign an empty string to a string offset in /home/apoturperu/public_html/wp-includes/user.php on line 41
[18-Jan-2023 14:42:51 UTC] PHP Warning:  Illegal string offset 'user_login' in /home/apoturperu/public_html/wp-includes/user.php on line 56
[18-Jan-2023 14:42:51 UTC] PHP Fatal error:  Uncaught Error: Cannot create references to/from string offsets in /home/apoturperu/public_html/wp-includes/user.php:56
Stack trace:
#0 /home/apoturperu/public_html/wp-login.php(806): wp_signon('', '')
#1 {main}
  thrown in /home/apoturperu/public_html/wp-includes/user.php on line 56

That is all I got so far. Hope you can help me with this.
Thanks in advanced!