Correctly configure mbstring for Bitrix site on PHP 7.3?

Question

1C-Bitrix

Good afternoon.
There was a problem with the work of the bitrix site on php 7.3.
The site is set in utf-8 encoding, utf-8 encoding is specified in the hosting settings.
If you specify in .htaccess

<IfModule mod_php7.c>
  php_flag session.use_trans_sid off
  php_value max_input_vars 10000
  php_flag default_charset utf-8
  php_value mbstring.func_overload 2
  #php_value display_errors 1
</IfModule>

I see this in the test results:

It's strange, because I indicated default_charset utf-8, but the testing tool still swears that this value is "0"
If I insert just the set of rules I used earlier (for php 5. *)

php_flag session.use_trans_sid off
  #php_value display_errors 1
  php_value mbstring.internal_encoding utf-8
  php_value mbstring.func_overload 2
  php_value default_socket_timeout 60
  php_value max_input_vars 10000
  php_value opcache.revalidate_freq 0
  php_value pcre.recursion_limit 1000
  php_value post_max_size 5M
  php_value upload_max_filesize 5M
  php_value memory_limit 128M
  php_value max_execution_time 300
  php_value max_input_time 300
  php_value session.gc_maxlifetime 1200
  php_flag session.use_trans_sid off
  php_flag default_charset utf-8

then I see a slightly different error

Tell me what I'm doing wrong?
UPD
Adding to /bitrix/php_interface/init.php ini_set('default_charset', 'utf-8')did not help. I solved the problem by rolling back to PHP 5.6. Apparently, something in bitrix is ​​not yet ready for correct operation on 7.3. Or maybe hosting is not suitable. Thanks for the advice!

Answer 1

Try to install an update on your CMS, apparently you have something old, this functionality has long been declared obsolete.
https://www.php.net/manual/en/mbstring.overload.php

Warning
This feature has been DEPRECATED as of PHP 7.2.0. Relying on this feature is highly discouraged.
Note:
It is not recommended to use the function overloading option in the per-directory context, because it's not confirmed yet to be stable enough in a production environment and may lead to undefined behavior.