I have 2 Path objects that I've applied some filter effects to: an ear, and a question mark (see picture). After applying some random noise and texture filters, I put a Felt Feather distortion filter on the 2 objects. The question mark turned out exactly how I want it, but the ear did not. My goal is to get the ear to have a similar X-axis warping as the question mark. I've now selected ONLY the ear, and tried to apply a 2nd Felt Feather filter on top of the existing filters. However, any edits I make to that 2nd filter now affects the question mark as well as the ear. How do I get the filter to ONLY apply to the ear, and leave the question mark alone? They are on separate layers. I've tried going into the filter editor, but don't really understand the right-hand section of the filter editor where it mentions Source Graphic.

I'm on a 2019 Macbook Pro running Big Sur, with Inkscape 1.2 installed via the dmg installer.

Currently filters cannot be chained into a new entity as far as I know. Objects can have only one filter applied on.

To achieve multiple filters on the same thing, you need to create groups.

Apply filter, group it -ctrl+g-, then apply filter on the group (consisting a single filtered object).

In addition, transformations can affect the rendering of filters. If you stretch the group, the filtered object will appear stretched, 

and not as the same filter applied on a stretched group.

Also, if the object inside the group isn't stretched, but the group previously was -pasted it into the group after theresizing- the filters will still appear stretched.

So to achieve the desired look, you need to make sure those are contained within groups without any interfering transformations.

Not sure about the  mentioned filters though. By the look theyare both based on fractal noise, but one was set to different size value for x and y.

Just a wild guess; is the question mark a shape and the the ear just a bunch of strokes perhaps and if yes will Path->Stroke to Path make a difference?

I already converted it to a path. The grouping tip worked, thank you!