Yes actually. I had that bug come out of nowhere a few days ago, it's the bottom frame of the tooltip of an item you've clicked on.
I don't know if it will resolve it for you, but if you're using the addon "Inventory Insight" what worked for me was to do as follows :
In your Addon Settings, go look in that addon settings in the "Tooltips" section and set "Show Info in Separate Frame" on OFF.
I hope it will help !