I have recently updated the THEME of the forum. However this was a couple of days before google had cached this age. Google Search console seems to have its own cached pages, and insists on using those for "LIVE" test, while the google online tools do pull the live page.
This must be a google bug.
Some of these reports do have inaccurate results - there are often cases where you get an error and then it goes away.
A test would be if Google is using the data to display a rich snippet. If it is, then I wouldn't worry about it.
Google Search Console gave again the same error, on pages that it says where crawled just yesterday, Sept 28th. Google keeps crawling the wrong version of the page. This must be a Google bug.