Hi
With PHP 8.1, Joomla 3.x on is not ready for it so it will throw deprecated /warnings messages for core files of Joomla too.
Regarding to template, I fixed these messages for your site:
Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /bitnami/joomla/templates/ja_mixstore/html/modules.php on line 35
Deprecated: htmlspecialchars(): Passing null to parameter #1 ($string) of type string is deprecated in /bitnami/joomla/templates/ja_mixstore/html/modules.php on line 41
I updated the same file:
//$badge = preg_match ('/badge/', $params->get('moduleclass_sfx'))? '<span class="badge"> </span>' : '';
$moduleclass_sfx = $params->get('moduleclass_sfx');
$badge = '';
if ($moduleclass_sfx !== null) {
$badge = preg_match ('/badge/', $moduleclass_sfx) ? '<span class="badge"> </span>' : '';
}
//$moduleClassSfx = htmlspecialchars($params->get('moduleclass_sfx'));
$moduleClassSfx = '';
if ($moduleclass_sfx !== null) {
$moduleClassSfx = htmlspecialchars($moduleclass_sfx);
}
I also see the error from 3rd party extension on your site called: Shortcode Ultimate plugins:
JROOT/plugins/system/bdthemes_shortcodes/config/inc/tools.php:294
I temporarily disabled these plugins so your site can work, you should contact the provider of this extension to get update for PHP 8.1
and J2Store as well:
Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in /bitnami/joomla/administrator/components/com_j2store/models/cartitems.php on line 38