What does JD mean?

[Take'n'Time2M'Self]

the changes on some characters say that the JD has been increased, what does that mean?

[Naiba]

Clearly it stands for Jar Damage, The ability for the characters to open the lids on tightly sealed jars with far less difficulty. Opening a jar with hooves is a big ask, after all.

(JD: Just Defend, seen in Capcom vs. SNK 2, Guilty Gear, BlazBlue, among other games. Press back as the opponent’s attack lands to block while recovering faster. - according to SRK from a quick google search.) This maybe? I don't get in what way that would be 'increased' though, still very new to fighting games.

[Astral]

Juggle Decay, the little green bar under your health bar. Once it's full, the character becomes heavier with each hit, making them harder to combo. It has some other quirks that I'm not completely certain about, but it's the infinite prevention system this game uses. When it's full, hits cause red sparks on the opponent. JDG is Juggle Decay Gravity, which just means how much gravity is added when they are hit by certain moves once the bar is full.

[Petralicious]

JD being increased means it fills the green bar (akin to drama bar in Skullgirls) more, and triggers super heavy gravity on the opponent earlier.

[cathead]

Just for informational purposes here's what all the Juggle Decay system does:
-When the bar is filled, each hit increases the gravity on the opponent.
-The opponent also, if standing, immediately goes into an airborne state
-Hard knockdowns no longer apply on specials/normals that normally do a hard knockdown
-Super still give a hard knockdown if juggle decay is filled.
-Staggers are also shortened