@Infinite_Power Hello and welcome to the forum
Please use a new topic for a new problem in future. It makes things much neater and easier to follow.
Version 4.4.8 can’t animate a transform mask. You need to use the 5.0.0-beta2 that you can download from the links here, in the Download section near the bottom of the page:
Second Beta for Krita 5.0 | Krita
Please read the warnings via the link to beta1 at the top of the page.
The screenshot you show is for adding an opacity keyframe to a Transform Mask in 4.4.8, which can’t be done because it doesn’t make sense.
If you use the 5.0.0-beta 2 then you’ll see this if you press the ‘+’ button on the top row of the Animation Curves docker when a Transform Mask is selected in the Layers docker or Timeline:
The orange frame marker can then be moved along the top to a different frame to create a second animation transform keyframe for the parameters.
This facility is in early stages of development and some aspects of it are confusing and difficult to manipulate.
I suggest that you limit yourself to Position and Rotation and remove any parameters that you’re not immediately working on by turning them off with the eye-visibilty icons.
The up-down and left-right arrow icons are very useful for range scaling.