I upgraded to LrC v11 about a week ago (not sure if I used it immediately thereafter). Today I imported RAW Fujifilm files (.RAF) and a few JPEGS. As soon as I applied a star rating (or an edit such as cropping, rotate) the down arrow icon appears on the thumbnail with the message "Metadata file needs to be updated." To test, I went to an older folder with Canon files (.CR2) and changed a few ratings - same thing, down arrow and update message. Just basic stuff you do when importing. The upgrade was seamless, no issues; I chose to remove old versions and retain settings for all of my Adobe products (PS, Bridge and RAW). I see no relavent options in Edit > Preferences. Anyone have a guess to what's going on?
The 'down-arrow' badge you mention is a flag to indicate that metadata associated with file has changed. It can be toggled on/off in View Options (Library > View menu). I've included a screenshot below for reference.
As to what's 'going on' - the down-arrow badge is indicating that you have made a change or changes to a file's metadata (e.g. ratings, labels, keywords, IPTC, develop settings, etc) that haven't yet been saved to an XMP sidecar (or DNG, PSD, TIFF, JPEG). If you're happy with the info being stored only in the catalog (many users are), then the badge can be disabled.
The default for the badge is for it to be enabled, but users who don't care/need to save the metadata to XMP or file usually disable it. I suspect yours have been reenabled during the 10.4 to 11.0 update, possibly due to preferences being updated
Maybe I wasn't clear. I know what the badge is all about. The problem is that it's showing up when it never used to ...i.e. it shows up when even a small change is made. After putting up with this for a month it seems that LrC is just slow in updating files and/or its database (yes, I optimize the database weekly). I'll just have to live with it.
The badge should appear if any metadata is added/changed/deleted or you edit the image in Quick Develop or Develop module. If the badge irritates, then just switch it off as per my earlier screenshot.