Blocks are overlapping

Do you use Safari as your browser? Then this bug in this browser could be the cause: https://www.ads-software.com/support/topic/classic-editor-add-new-post-broken-in-new-safari/

A possible solution is also linked at the bottom of the topic as long as Safari has not provided an update.

yes, this is because safari. thank you for help.

it is resolved. I add this css snippet from @misterelvis fix plugin

https://telltec.ch/projects/safari-18-wordpress-classic-editor-fix/

/**
 * Add the needed CSS to admin head
 */
function add_fix_css_to_admin_area() {
    echo '
    <style>
        /* Temporary Fix for classic editor bug in Safari 18 - Addded by Safari 18 Classic Editor Fix plugin  */
        #postbox-container-2 { clear: left; }
        .index-php #postbox-container-2 { clear: none; }
    </style>
    ';
}

add_action('admin_head', 'add_fix_css_to_admin_area');

best regards