Beyond PageSpeed Insights: What tools do you use to benchmark the impact of heavy third-party JS on Core Web Vitals?

Hey everyone, I’m currently auditing a utility site that saw a massive traffic drop (90%) immediately after integrating a third-party ad network (Adsterra). I suspect the ad scripts are causing significant layout shifts and blocking the main thread, but I'm struggling with data consistency . Google PageSpeed Insights (PSI) gives me wildly different scores every time I run it—ranging from 30 to 70—likely due to the dynamic nature of the ad delivery. I’m looking for tool recommendations that excel

• Beyond PageSpeed Insights: What tools do you use to benchmark the impact of heavy third-party JS on Core Web Vitals?
  r/webdev

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