A few days ago, I searched for "traveling" in some forum or maybe thread. (Actually, I think I did. I don't recall for sure, and I certainly don't recall which forum or thread.) Today, and for the past few days, I have found posts that contain the word traveling highlighted in red. Here's an example, from UA Launches World's First Free Transatlantic COVID-19 Testing pilot program.

(If I posted that by copy and paste, the red disappeared, so I pasted it as a .png.) I have looked at the search page and the Keyword(s) field is empty. Any idea what is happening?

[Edit. That paste didn't work. But if you look at the first post of the linked thread and imagine every instance of the word traveling is red, that's what I'm talking about.]