When opening the user logs in ACP, I get a 500 server error and a related PHP error:
PHP Fatal error: Uncaught Error: Unknown named parameter $log_data in /var/www/phpbb/phpbb/log/log.php:698
#0 /var/www/phpbb/phpbb/log/log.php(698): call_user_func_array()
#1 /var/www/phpbb/includes/functions_admin.php(2620): phpbb\\log
#2 /var/www/phpbb/includes/acp/acp_logs.php(132): view_log()
#3 /var/www/phpbb/includes/functions_module.php(676): acp_logs->main()
#4 /var/www/phpbb/adm/index.php(81): p_master->load_active()
thrown in /var/www/phpbb/phpbb/log/log.php on line 698
I'm not sure when exactly this appeared, probably with one of the latest PHP8 patch versions. I couldn't fine a definite bug in the code either. It's assured that the log_data field exists: https://github.com/phpbb/phpbb/blob/master/phpBB/phpbb/log/log.php#L668
Adding another isset() does not help. I assured that caches were cleared. Probably it's also a bug in PHP, but you guys might have better insights and ideas how do debug.
Only user logs are affected, moderator, admin and errors logs show up well. Maybe also the size is relevant? MariaDB and the webserver do not throw further errors.