Update Debian 11 to Debian 12.
Login to zabbix get many warnings in dashboard:
PHP option "post_max_size" 8M Minimum required size of PHP post is 16M (configuration option "post_max_size").
PHP option "max_execution_time" 30 Minimum required limit on execution time of PHP scripts is 300 (configuration option "max_execution_time").
PHP option "max_input_time" 60 Minimum required limit on input parse time for PHP scripts is 300 (configuration option "max_input_time").

File /etc/apache2/conf-available/zabbix.conf > /etc/zabbix/apache.conf need get update for php 8.x because there is only for php 5 and 7:

<IfModule mod_php5.c>
php_value max_execution_time 300
php_value memory_limit 128M
php_value post_max_size 16M
php_value upload_max_filesize 2M
php_value max_input_time 300
php_value max_input_vars 10000
php_value always_populate_raw_post_data -1
php_value date.timezone Europe/Warsaw
</IfModule>
<IfModule mod_php7.c>
php_value max_execution_time 300
php_value memory_limit 128M
php_value post_max_size 16M
php_value upload_max_filesize 2M
php_value max_input_time 300
php_value max_input_vars 10000
php_value always_populate_raw_post_data -1
php_value date.timezone Europe/Warsaw
</IfModule>