Baseline component seems to show incorrect Baseline status or BCD is incorrect

[teoli2003]

Summary

Baseline provides information about the status of a feature.

It is displayed on subfeatures too.

This leads to incoherence: a feature can be marked as limited availability on a page where the subfeature is available for a long time. Example: https://developer.mozilla.org/en-US/docs/Web/CSS/:defined

As it is not clear in the banner that the feature and the subfeature are two different things, this leads to confusion to readers (we get report every week of errors)

URL

https://developer.mozilla.org/en-US/docs/Web/CSS/:defined

Reproduction steps

Trivial

Expected behavior

Either the banner should be displayed on the feature only and not the subfeature; or the banner should make it clear it is for the whole feature, to avoid confusion.

Actual behavior

The banner is confusing.

Device

Other (specify below)

Browser

Other (specify below)

Browser version

Other version (specify below)

Operating system

Other (specify below)

Screenshot

No response

Anything else?

No response

Validations

• I have read the Community Participation Guidelines.
• I have verified that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• I have checked that this is a concrete bug. For Q&A open a GitHub Discussion.

[LeoMcA]

Our current "sticking plaster" fix for this is to add problematic BCD queries to a blocklist, like so:

• fix(baseline): hide status from async-clipboard subfeatures #10345
• fix(baseline): add custom elements group to blocklist #10479

However, ultimately this is something we need to fix in collaboration with upstream, much discussion about showing per-feature rather than per-group baseline statuses has happened here: web-platform-dx/web-features#495

And publishing code to allow us to do those computations is happening here: web-platform-dx/web-features#544. It may be that we use this code to compute a Baseline banner for the BCD keys shown on each page, or it may be that we use this code to simply hide the group banner if there's a discrepancy - most recent discussion has tended towards the latter.