Yep, quite a number of things. From the standpoint of 'everything is OK, it's a jetting question,' it's still a bit iffy.
High revs with lack of power is probably lean, a 'flattening' effect (that would be not revving correctly) is likely rich.
Obviously you don't want to be doing a whole lot of WOT running if there is a question of being too lean.
If it's stock jetted (and mechanically sound) it's almost certainly rich.
The mixture ring at the base of the insulator is the way to gauge air/fuel mixture.
Under the heading of 'experiment', you could try some 20:1. If the condition improves you've shown the bike to be rich.