I'm not sure if this is a bug or intended, but if it is a bug it should be fixed back to how it was.
If it was intended, this is honestly a bad fix to being able to sprint jump while casting a warmup.
I can see how this is an idea to counter classes such as Cleric so they cannot kite as well while using their healing spells. But the fact that their big spells such as SacredTouch already have a long warmup already counters their kiting since they are slowed for a much longer period of time. Having increased slowness/negative jump boosts also affects other classes such as Bloodmage, which requires being able to kite while casting spells. Imo, it was fine the way it was before this change. You also have to consider speed potions, which pretty much majority of the people who pvp has, that can also catch up to these people trying to cast a spell.