Thank you for looking into this. The full error in wp-content/debug.log is
[23-Jul-2021 12:35:20 UTC] Chyba wordpress databázy Column 'ping_status' cannot be null pre požiadavku INSERT INTO <code>mozsk_posts</code> (<code>post_author</code>, <code>post_date</code>, <code>post_date_gmt</code>, <code>post_content</code>, <code>post_content_filtered</code>, <code>post_title</code>, <code>post_excerpt</code>, <code>post_status</code>, <code>post_type</code>, <code>comment_status</code>, <code>ping_status</code>, <code>post_password</code>, <code>post_name</code>, <code>to_ping</code>, <code>pinged</code>, <code>post_modified</code>, <code>post_modified_gmt</code>, <code>post_parent</code>, <code>menu_order</code>, <code>post_mime_type</code>, <code>guid</code>) VALUES (16, '2021-07-23 14:35:20', '0000-00-00 00:00:00', '', '', 'Automatický koncept', '', 'auto-draft', 'post', 'open', NULL, '', '', '', '', '2021-07-23 14:35:20', '0000-00-00 00:00:00', 0, 0, '', '') vykonanú get_default_post_to_edit, wp_insert_post
I cannot tell which file it came from, the database error does not say.
A very similar error has been also reported here https://core.trac.wordpress.org/ticket/51842. It does not happen on two other pages, where the pingbacks/trackbacks are disabled (but do not have WP Statistics installed). On the affected installation I also tried to replace all WordPress files from a fresh download, just to make sure it’s not corrupted, but it did not help.
