Two problems. +20 speed is a lot. Gamebreakingly so for e.g. classes with top speed of 75, or with speedy abilities like Ninja, Warrior generally, Rogue, Priest + Mystic with particular UTs. Yes, there’s Candy Ring but that is also too fast for some classes, and comes with nerfs so no-one would wear it all the time – while this has pretty decent stats apart from the boost.
More problematic is how would it interact with existing speedy abilities. E.g. if this triggered after a Warrior used their ability, would it switch off their ability, override it for a second, or do nothing as a Warrior’s speedy takes priority? What about the other way round if the Warrior uses their ability while slowed by this? Repeat for all class speedy abilities.
Speedy is already broken in the game. Ninja’s is broken in various ways, and in some places the way it interacts with the game for all classes is broken. E.g. I can perma-Speedy with my Priest and a t6 ability – with maxed wis and a decent pet it’s pretty easy. Except not in Labs, as any time you go through green your speedy gets disabled, even if you had it from an ability. Having a ring also able to modify your speed is likely to lead to many more bugs.