Many of my posts which have links to blog articles such as https://fharrell.com/post/po are having the URLs systematically changed to http://www.fharrell.com/p/blog-page.html which is not even a valid page. Help appreciated!
These links seem to have been in place at least since October 2020, at least one and a half year ago.
We can see this in the following archived webpage which contains the link
It is possible to dig further by using the database dump from stack exchange.
It seems very unlikely that the system can change the body text without leaving a trace in the post history. That history can already be viewed via the website and there is no trace in the history like user 'community' editing some link or style.
Anyway, if there would be such a change that did not show up in the post history then it should be still possible to see it in the database dumps. Because I have currently no access to my laptop, I can not perform that search.
The web address ending with
/p/blog-page.html is not so strange. It might stem from the blogspot webpage: https://feharrell.blogspot.com/p/blog-page.html
It could be possible that you wrongly combined two url's. This might explain why, as Whuber mentioned in the comments, only posts from 2017 have the error.
Other occurances (and potential explanation 2)
The link also occurs in comments
Some intuitive and simple approaches are discussed in BBR Chapter 16 - see link at fharrell.com/p/blog-page.html
And on twitter
Clinical trialists: please quit computing change from baseline. See BBR Chapter 14: http://fharrell.com/p/blog-page.html
On twitter it seems that also others have linked to the broken links:
I can't search this easily because I don't have a Twitter account and that makes Twitter evil towards me when I try to search it's pages. But anyway, those references might indicate that possibly you were using your website in a different mode with different links around 2017.
And yes indeed, the page
https://www.fharrell.com/p/blog-page.html used to exist back in 2017. Or at least, the internet archive seems to agree with me. This page can be found in the archives
On 27 December 2017 it looked like this: https://web.archive.org/web/20171227182433/http://www.fharrell.com/p/blog-page.html
On 18 January 2018 it was a 'page does not exist' webpage: https://web.archive.org/web/20180118062901/http://www.fharrell.com/p/blog-page.html