Link inaccessible objects to accessible versions
Where one object on a page cannot be made accessible, G190 puts a link to a conforming version next to it. Placement is normative rather than advisory here. W3C's test requires the link to sit directly after the non-conforming object in the linear reading order, or otherwise be associated with it, and the alternate has to convey the same information. Read the status carefully. W3C references G190 from no success criterion at all. It belongs to WCAG's conformance requirements, in the group of techniques for providing conforming alternate versions, which supports the first conformance requirement rather than any individual rule. So this is not a way to pass a criterion. It is the escape hatch WCAG defines for content you cannot fix, and using it puts the accessibility burden on the alternate version instead.
How we find it in an audit
Our reviewers tab past the object and check what comes next. A link mentioned only in a support article, a footer, or a separate accessibility page does not satisfy the placement requirement, however good the alternate is. Then we audit the alternate itself, comparing information and functionality against the original before checking it conforms.
How affected users experience it
The reader meets the object before they meet the link, always, because that is the order the page is read in. So a link placed anywhere else arrives after they have already failed to use the widget and concluded the site is broken. Directly after the object, they hear the alternative in the same breath as the problem, and the whole encounter takes seconds instead of ending in a support email.
Passes vs. fails
Passes
Directly below the widget sits 'Prefer a list? Choose your seat with the accessible seat picker', linking to an HTML version with identical seats and prices.
Fails
An embedded seating-chart widget invisible to assistive technology, with the HTML booking form mentioned only in a support article.
This guide is our interpretation of W3C technique G190: Providing a link adjacent to or associated with a non-conforming object that links to a conforming alternate version. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.