Baseline audit detects false-positive features triggered by internal gatherers

[rviscomi]

FAQ

• Yes, my issue is not about variability or throttling.
• Yes, my issue is not about a specific accessibility audit (file with axe-core instead).
• Yes, my issue is not answered by other FAQs.

URL

https://example.com/

What happened?

When running a Lighthouse audit on a completely static page with zero <script> tags (such as https://example.com/), the Baseline Features (baseline) audit reports 7 JavaScript web platform features attributed to https://example.com/:0:

1. page-visibility-state
2. long-animation-frames
3. layout-instability
4. abortsignal-any
5. nullish-coalescing
6. aborting
7. weak-references

Recorded Lighthouse Viewer report:
https://googlechrome.github.io/lighthouse/viewer/?gist=ea14135d469d87a7cc02933a47646162

These features originate from Lighthouse's own internal driver gatherers and performance observers (e.g. CLS/INP PerformanceObservers, AbortController, AbortSignal.any(), document.visibilityState) running in the inspected execution context, which increment Blink's UseCounter IDs for the document.

What did you expect?

Because https://example.com/ contains no JavaScript, the web-features / baseline audit should not report any JavaScript API features. Internal Lighthouse gatherers and driver scripts should not attribute Blink UseCounters to the audited page.

What have you tried?

1. Tested against a static site (https://example.com/) with zero scripts.
2. Verified that running headless Lighthouse without interactive DevTools scripts avoids certain runtime gatherer collisions, while DevTools / in-page gatherers trigger Blink UseCounter detections that get recorded in audit.details.items.
3. Verified the exact items and source locations in the exported LHR JSON.

How were you running Lighthouse?

Chrome DevTools

Lighthouse Version

13.4.0

Chrome Version

152.0.7977.65

Node Version

No response

OS

No response

Relevant log output