Hi!
There are two tools that you could try to use on this. You'll need Maya 2022 or higher to have them available.
Select an affected joint and in the Grapheditor under Curves you'll see a tool called "Peak Removal Filter".
This tool will try to remove spikes from your curves that seem too extreme or irregular over a short period of time. Sadly apart from setting what curves you want to filter and over which timeframe, it doesn't give you many settings.
The other tool is the "Smooth Filter (Gaussian)". You find it in the UI right over the Peak Removal filter. This tool basically just smoothes out your curves. This can be used to get rid of some jitter, by trying out different values you can probably get some pretty good results, but since it smoothes out everything, it will also make your animation floaty, so it is to be used with caution.
Depending on your curves, these two tools can give you a pretty good starting point. After that, you'll probably need to do oldschool cleaning on the rest. Select the joints with the jitter on them, look at the curves in the graph editor. Jitterning like this is fairly easy to spot, as you will have bit up and downs in your curves over very short times. select the keyframes in the places where most jitter happens, Ideally between two frames of the same value and delete those keys.
I hope it helps!
