How does the skip option work in syntax (.yaml) files?

Description of the problem or steps to reproduce

I'm editing some of the syntax files to make them consistent with my other editors, and I've been trying to utilize the skip option but I can't get it to work.

Trying with a simple test json.yaml file:

filetype: json

detect:
    filename: "\\.json$"
    header: "^\\{$"

rules:
    - json.object:
        start: "{"
        end: "}"
        skip: "6"
        rules: []

and a json file like this:

{ test stuff 6 }

I would expect that everything except the 6 would be highlighted, but even the 6 is highlighted.

Specifications

Version: 2.0.12-dev.71
Commit hash: ceaa143c
Compiled on July 16, 2023
OS: Arch
Terminal: Alacritty

Reproduce the report using the shown json.yaml syntax file and the sample json input. Then trace how the syntax engine handles the skip option and compare that behavior with the expected highlighting; done means either the option works as described or its documented behavior is clarified.