"For others" (probably not jquery or vanilla javascript ?) response by basickarl did the trick for me.

I was looking for a simple script that is able to uncheck all "vendor" list in cookie popups, from Firefox / Chrome devtools > console tab.

The solution with $(jquery) didn't do the trick, since all implies that that website has jquery loaded.

In my case jquery was not present, so the simple oneliner solution that did the batch unchecking was the one menitoned:

document.querySelectorAll('input[type=checkbox]').forEach(el => el.checked = false);