wpcf7_uploads-XXXXXX.tmp flooding system tmp

Issue: My system’s tmp dir is flooded by files with the following name pattern: wpcf7_uploads-XXXXXX.tmp containing the content for the content of the .htaccess file assembled in includes/file.php:289:

# Apache 2.4+
<IfModule authz_core_module>
    Require all denied
</IfModule>

# Apache 2.2
<IfModule !authz_core_module>
    Deny from all
</IfModule>

Setup: Plugin vers. 6.1.6, WordPress 7.0, php 8.5. WP File system is only available via FTP. WPCF7_UPLOADS_TMP_DIRnot set.

define( 'FS_METHOD', 'ftpext' );
define( 'FTP_USER', 'XXX' );
define( 'FTP_PASS', 'XXX' );

I assume something with wpcf7_upload_tmp_dir is not working as expected.

Thanks for your help.