The date of the last modification is declared through both the OpenGraph and Schema.org protocols, as well as through the XML sitemap and is even mentioned in the content. I can suggest two other ways to declare it in a semantic way. It should be kept in mind that the decision remains with Google in this case.
I'll recommend you add it to the content in a slightly more semantic way using HTML. What I recommend is to add, for example, after the publish date something like this:
Each of the dates should then be marked up with the time HTML tag. It is also necessary to use the datetime attribute, which provides the date in a machine-readable format. Add the date in ISO 8601 format. For example:
<time datetime="2023-03-22">March 22, 2023</time>
Search engines can use this information to better understand the content of your site and improve the accuracy of search results.
The other option is by implementing an HTTP header for the blog articles. This is HTTP header is Last-Modified, which purpose is to indicate the last time that a particular resource (web page in this case) was modified. Search engines can also use the Last-Modified header to determine whether a page has been updated since it was last crawled. This can help search engines ensure that their index is up-to-date, and can improve the accuracy of search results. An example of such an implementation can be done via a WordPress plugin. One such plugin is: WP Last Modified Info