Why is it being said that Jay used Velocity's earlier variants? 

More to the point, Velocity 6 was something that Caitlin Snow and Harrison Wells 2 created very recently in universe, so how would it be the cause of Jay losing his speed if it only existed for like 3 weeks or so?

When Caitlin and Jay were talking about how he actually lost his connection to the Speed Force didn't he say that he made something similar to augment his speed? 

Plus Harrison Wells 2 said that Velocities 1-5 were failures, as in they didn't work due to him not thinking of making it increase the oxygen intake of a speedster or something, and with Caitlin's help he finally made one that worked, this was Velocity 6, the first successful one.

So why are we saying that Jay used Velocities 1-5 when they didn't work, and that Velocity 6 is what caused him to lose his powers when it was just made.

Maybe call it "Jay's speed serum"