Users say the page jumps around while it loads, but your synthetic audit reports no layout shift at all. How do you find it and fix it?

Short answer

Layout shift is a field problem: it depends on network speed, consent banners, ads and personalisation that a lab run never sees. Collect layout-shift entries from real sessions with their source nodes, then reserve space for whatever moved.

Keep core web vitals explicit in the answer because that is the concept the interviewer is actually trying to test. A good core web vitals explanation names the trade-off, the failure mode, and the evidence you would use before choosing. Use core web vitals once more at the decision point so the answer reads as judgement rather than a detached example.

Keep core web vitals explicit in the answer because that is the concept the interviewer is actually trying to test. A good core web vitals explanation names the trade-off, the failure mode, and the evidence you would use before choosing.