I’ve just noticed I get a similar error. If I search my site, and a blog post without a Featured Image is found, this error comes up:
Warning: Trying to access array offset on value of type null in /[path-to-wp-removed]/wp-content/themes/kahuna/includes/loop.php on line 295
I’ve found that the server is running PHP 8.1, and if I change it to 7.4 then the error goes away.
I think this is because in PHP 7 if you try to get the contents of an empty (or non-existent, perhaps) array you get a response of “null”, whereas in PHP 8 you get *nothing*, and so an error. Willing to bet your errors are for the same reason, and if you can change your server to PHP 7.4 it’ll fix it for now until Kahuna gets updated to work with PHP 8+ fully.