While in the Dungeon, some players might currently see an exclamation mark next to their Gem count. Tapping on it opens an error message that reads the following:
"At least one of your recent purchases was not processed correctly. For more information please contact support."
If you have not refunded any of your recent purchases and have not run into any issues with them lately, you should not worry about this message. This is a bug and your purchases should not be affected.