Uncaught PHP Exception Error: "Call to a member function dirname() on null" at /var/www/html/web/modules/contrib/search_api_attachments/src/Cache/Files.php line 79

MR rolls back the removal of the promoted constructor parameters that occurred in this commit.

https://stitcher.io/blog/constructor-promotion-in-php-8

Pushed a small change to separate constructor params on to newlines to improve readability. This should definitely go in. I'm going to open a new issue for other issues with that class too (it's using FileSystemInterface::EXISTS_REPLACE)

Thank you for this finding
it is now merged :)

here it is https://www.drupal.org/project/search_api_attachments/releases/10.0.3 →

Thank you @izus for your quick response!