2️⃣ Apply Display Conditions (Elementor → “Advanced → Responsive → Custom Display Conditions”)

This is the magic trick.

Select the SEO Posts widget

Go to:

Advanced → Display Conditions (or Visibility)
(If you use Elementor free, this option is inside “Visibility” addon or within “Dynamic Conditions” plugin)

Set:

✔ Show When → Post Has Category → SEO
Hide otherwise.