Opening the issue after quickly chatting with mgol on IRC

I made a branch to update jQuery to v3.6.0 in twbs/bootstrap#33243. I notice our BrowserStack tests fail consistently on Internet Explorer 10 and 11. v3.5.1 works fine.

git clone https://github.com/twbs/bootstrap.git -b v4-dev-xmr-update-jquery
npm i
npm run js-test-cloud #assumes you have BrowserStack credentials set up

The failures seem to point to https://github.com/twbs/bootstrap/blob/v4-dev/js/tests/unit/dropdown.js#L860 and https://github.com/twbs/bootstrap/blob/v4-dev/js/tests/unit/dropdown.js#L870

EDIT: using jQuery v3.3.1 also works fine.