I know this seemed like just a quick joke that didn’t have any specific reasoning behind it, but hear me out
Point 1: Lloyd is the one that released Meowthra
(And it is implied that when meowthra enters the scene, the Shark Army doesn’t have to much of a good time)
From “The Ninjago Movie, The Essential Guide”
Point 2: General 1/prior two’s (Let’s just call her Gen for simplicity) design changes noticeably.
A list of changes, starting from least important to most important.
1: Hair is in a different position. This may mean nothing since the character’s hair in this movie can move.
2: Frills are down and appear broken. This would be one way to show that she was in a fight.
3: Medallions slightly melted signifying great heat. Another example is the prior General 1,
His medals are melted and his clothes are full of burns. Presumably from when Garmadon fired him, out of the volcano base.
“… He enjoys glory, power, and a chance to bask in Lord Garmadon’s evil shadow. There’s just one snag. If he upsets his boss, he will be fired. From a volcano. Just like every other General #1 before him.”
A speech bubble from him on the same page
“Wait, Sir! I was only trying to help!”
So, we can presume he’s booted and Gen takes his place.
4: There is a burn on Gen’s lower right side and the belt is broken. You know what is probably hot? The laser that Meowthra followed. And who wielded the laser? Lloyd Garmadon.
5: The most important. Look at Gen’s arms in the screenshot. One white glove, one black glove. Both of her hands usually have white gloves.
5.1: She also has a much different expression than in the picture with the cup.
Point 3: Why the different gloves?
Well, if the laser pointed at her, Meowthra most likely attacked her. (It was also aimed at her right side, where she is missing the white glove)
This is where it gets into more theory territory,
Meowthra attacked her and she lost her right arm.
This would explain a lot. Her motive to attack Lloyd. Surely if Garmadon joined Lloyd she would too, right? Unless she had something against him, like losing a limb. Why did Lloyd lose his right arm specifically? Gen wanted revenge.
That is my theory, which i’m pretty confident of. It explains her motive and why it was Lloyd’s right arm. I encourage questions or comments!