Google has updated the help document for file types indexable by Google to include Comma-Separated Values (.csv) in the list. I doubt Google was not bale to index those files before, and I wonder if this was just a documentation change but not a change in what Google was able to index?

The help document is over here and you can find the new line for CSV files under the Text (.txt, .text, other file extensions), including source code in common programming languages section.

You can see in the March copy it did not have CSV listed. It also didn’t have these two sections:

• Various video formats: 3GP, 3G2, ASF, AVI, DivX, M2V, M3U, M3U8, M4V, MKV, MOV, MP4, MPEG, OGV, QVT, RAM, RM, VOB, WebM, WMV, and XAP
• Various image formats: BMP, GIF, JPEG, PNG, WebP, and SVG

But with those, I am pretty sure Google was able to index all of those without issues, so those were a help document update versus a Google Search functionality change.

Update: This is new not just in the help document but also new in terms of now Google can index CSV files:

New new, not just new doc :).

— John is updating his unnamed profile name #ok (@JohnMu) August 25, 2023

Although, CSV files are not coming up yet:

I can’t surface any csv files yet via site queries (across sites). Maybe that’s still being worked on. 🙂 pic.twitter.com/2yHtTUFKH9

— Glenn Gabe (@glenngabe) August 25, 2023

Forum discussion at Twitter.