I have just discover something strange with my category urls.
If I have, for example, https://www.myweb.com/category/category-slug or https://www.myweb.com/my-category-slug using Yoast SEO for removing /category/ from url, I can add in the navigator something like https://www.myweb.com/ddddd/category-slug or https://www.myweb.com/category/ddddd/category-slug (or any other word instead of ddddd) and it continues working the same!

Is this normal?? How can I avoid this problem?

Thank you in advance

Can you confirm you are using the latest version of WordPress 5.6 and Yoast SEO for WordPress 15.6.2?

Just to clarify, you have enabled the remove categories prefix feature, and your concern is that for https://website.com/category/category-slug/, it works and redirects to https://website.com/category-slug/, but if you modify the URL in the browser to something like https://website.com/xxxxx/category-slug/ (where xxxxx is any word or phrase) and reload it, it still just redirects to https://website.com/category/? Are we understanding this correctly?

In the help center article, there is a warning:

Note: This feature can cause unexpected URL behavior and is not recommended in most cases.

So we definitely would recommend testing this out on a staging site and then determining if you want to continue using the feature.