Hi Johnny,
Pages from SPPB 3.x do not have this feature (and field for date in database), and will not get it. Probably 3.8.10 was the last update of this 3.x series.
Add this manually, for example by using Text addon. I know... but it always works, and guests do not see how it was added, right.
In SPPB 4.0.x yes, it's added as meta tag even for pages:
<meta property="article:published_time" content="2021-02-10 07:39:23"/>
<meta property="article:modified_time" content="2023-04-27 06:14:35"/>
and this information is stored in database.