The black one is the Bootstrap tooltip. The gray is a browser specific way of showing title attribute of the tag (it's black on my browser).

The black/fast one is to be preferred.

Do you want reports in this tracker where the grey one appears?

There are a system to use bootstrap title everywhere .
But sometimes : we need title by "alt" image inside the link etc ...

Then order must be good :)

@pmonstad : think you can wait for this one to be fixed.