This isn't a critical issue, but it seems that when you "hide but make available" an activity while using Tiles format, it writes the "available but not shown on course page" tag twice. I am using Fordson and Tiles in Moodle 3.9.6.
- Switching to another format (like weekly or topic) removes the duplicate.
- Removing the availability but still hiding also removes the duplicate tag.
I haven't tested outside of Fordson.