UI locale is detectable by button width
We got a HackerOne report by xiaoyinl outlining steps to detect the UI locale of the browser despite the user not changing the
If one specifies a button
<input type="submit"> without a "value" property, the default text of the button depends on the UI language. And the resulting width of the button can be measured.
We should not only focus on that particular button but should look closer whether other UI parts are suffering from the same problem.