Avoid serving legacy Javascript to modern browsers

[jphorn]

Describe the bug

My GTMetrix performance report is reporting "Avoid serving legacy Javascript to modern browsers" for /dist/js/frontend.js, specifically for Array.prototype.includes (although this might be incorrectly reported).
Would it be possible to investigate?

Steps to Reproduce

More info here: https://gtmetrix.com/avoid-serving-legacy-javascript-to-modern-browsers.html

Screenshots, screen recording, code snippet

Environment information

No response

WordPress information

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Code of Conduct

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