superbear1

This doesn’t look like Rank Math behavior, especially since the free version doesn’t run any bulk background updates like that.

A pattern where dozens of posts get their post_modified updated at the exact same minute usually points to something automated outside Rank Math. A few things you should check:

• Other plugins (especially SEO, cache, security, auto-tagging, or internal linking plugins) – some of them run cron jobs that “touch” posts without changing visible content
• Scheduled cron jobs – even if you only see one Rank Math task, other plugins or server-level cron jobs may not be obvious
• Theme functions – custom code in functions.php can sometimes update metadata silently
• External tools / API access – if you use any automation tools, REST API integrations, or scripts, they can trigger bulk updates under one admin user
• Security issue – since all changes are under the same admin user, it’s worth checking login logs and ensuring the account isn’t being used by a script or compromised

One quick way to narrow it down:

• Disable all plugins except Rank Math and monitor
• Then enable plugins one by one to identify the trigger

Also check your hosting panel (cron jobs section) — I’ve seen cases where hosting-level cron runs every few minutes and updates posts in bulk.

Since your content isn’t actually changing, something is likely just updating metadata or “touching” posts programmatically, which forces WordPress to update post_modified.