I recently migrated a Linux VPS from a shared hosting to a new one. I installed the new version of PHP 8.2 on the new host because the hosting told me that version 8.1 was obsolete as of January.

Since then I have had problems with the Solitude theme, specifically with the plugin mentioned above, because when I activate it the theme's frontend doesn't appear, but I can access the backend. If I deactivate Penci Shortcodes & Performance the problem disappears. Since I see that it is a mandatory plugin, what can I do?

I've also been looking at tools/site health and the permissions section shows the following:
The WordPress main directory Editable
The "wp-content" directory Editable
The uploads directory Editable
The plugins directory Editable
The themes directory Editable
The sources directory Not editable
The essential plugins directory Editable

Then I introduced debug mode in wp.config.php and the debug.log gives me the following error:

[04-Jan-2025 19:03:27 UTC] PHP Deprecated: Creation of dynamic property DOMDocument::$xpath is deprecated in /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-content/plugins/penci-shortcodes/pagespeed/inc/process.php on line 207
[04-Jan-2025 19:03:29 UTC] PHP Fatal error: Soledad\\PageSpeed\\RemoveCss\\Sanitizer::parse_selectors(): Cannot use output buffering in output buffering display handlers in /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-content/plugins/penci-shortcodes/pagespeed/inc/remove-css/sanitizer.php on line 170
[04-Jan-2025 19:03:30 UTC] PHP Fatal error: Uncaught Error: Class "Elementor\\Plugin" not found in /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-content/themes/soledad/inc/template-builder/other/404.php:9
Stack trace:
#0 /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-includes/template-loader.php(106): include()
#1 /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-blog-header.php(19): require_once('...')
#2 /var/www/vhosts/vivirelsenderismo.com/httpdocs/index.php(17): require('...')
#3 {main}
thrown in /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-content/themes/soledad/inc/template-builder/other/404.php on line 9
[04-Jan-2025 19:03:30 UTC] PHP Deprecated: Creation of dynamic property DOMDocument::$xpath is deprecated in /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-content/plugins/penci-shortcodes/pagespeed/inc/process.php on line 207
[04-Jan-2025 19:03:32 UTC] PHP Fatal error: unserialize(): Cannot use output buffering in output buffering display handlers in /var/www/vhosts/vivirelsenderismo.com/httpdocs/wp-includes/functions.php on line 650