Not seeing that here. Perhaps the compromise is on your end.

It's subtle, you probably missed it:

  $ curl -s http://www.slrn.org | egrep Payday\|National
  Davis has returned to develop slrn again&nbsp;<a href="http://fastonlinepayday.com/">Fast Online Payday Loans</a> and after much work has
  subscribe both slrn-admin and slrn-user <a href="National-cash-advance.html"> National cash advance</a>. For questions about slrn that

Wow I did totally miss those. I was looking for banner ads or something. Scanning over the page I didn't even notice those bits of text.

Same. The link is HTTP so it looks like GP is getting some sort of malicious ad insertion.

I see it on two different networks. They’re not big ads, just hyperlinks subtly inserted into the text.

Yeah, I tested multiple networks. It's not on my end.

archive.today sees it too:

https://archive.vn/JOBcZ