Hi, our error log is filled with these errors. How can we fix that?

[Sun Sep 14 14:40:50.956130 2025] [proxy_fcgi:error] [pid 1693237:tid 1693262] [client 2001:41d0:a:2d0e::1:0] AH01071: Got error 'PHP message: PHP Fatal error: Uncaught TypeError: count(): Argument #1 ($value) must be of type Countable|array, string given in /var/www/vhosts/anarchistischefederatie.nl/httpdocs/wp-content/plugins/w3-total-cache/Generic_Plugin.php:603\nStack trace:\n#0 /var/www/vhosts/anarchistischefederatie.nl/httpdocs/wp-content/plugins/w3-total-cache/Generic_Plugin.php(603): count()\n#1 [internal function]: W3TC\\Generic_Plugin->ob_callback()\n#2 /var/www/vhosts/anarchistischefederatie.nl/httpdocs/wp-includes/functions.php(5471): ob_end_flush()\n#3 /var/www/vhosts/anarchistischefederatie.nl/httpdocs/wp-includes/class-wp-hook.php(324): wp_ob_end_flush_all()\n#4 /var/www/vhosts/anarchistischefederatie.nl/httpdocs/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()\n#5 /var/www/vhosts/anarchistischefederatie.nl/httpdocs/wp-includes/plugin.php(517): WP_Hook->do_action()\n#6 /var/www/vhosts/anarchistischefederatie.nl/httpdocs/wp-includes/load.php(1304): do_action()\n#7 [internal function]: shutdown_action_hook()\n#8 {main...'