Feature request summary

Warn web developers that they should avoid unload events and use visibilitychange instead.

I am willing to work on this. Seems like a relatively easy audit to implement.

What is the motivation or use case for changing this?

https://developers.google.com/web/updates/2018/07/page-lifecycle-api#legacy-lifecycle-apis-to-avoid

How is this beneficial to Lighthouse?

It's an easy-to-detect change that could help improve the reliability and performance of websites.

P.S. How is this beneficial to Lighthouse? is a strange phrasing. Seems like it should be How is this beneficial to the web?