Extra Spacing in a nested FontVariation does not work

[kimkanu]

Godot version

4.2.dev3

System information

Godot v4.2.dev3 - macOS 13.4.0 - Vulkan (Mobile) - integrated Apple M1 - Apple M1 (8 Threads)

Issue description

Probably related to #58340

When a FontVariation has a FontVariation in it as a fallback font, Extra Spacing values are overriden by the parent's one. Transforms and Embolden values seem to be fine.

Steps to reproduce

1. Create a Label.
2. Create and set a FontVariation as the font of the label node.
3. Create and set another FontVariation as a fallback font of the font of the label node.
4. Manipulate Extra Spacing values of the fallback font (such as Glyph) and there are no visible changes. If the parent has changed extra spacing values, then it affects the child fallback font too.

Minimal reproduction project

font_variation_bug.zip

[gu-fan]

in 4.2.1 stable, this issue seems still remains.

chaning spacing_glyph in subresource seems does working after test.

But changing spacing_top or spacing_bottom in subresource does not working.