WPT details: The Web Platform Tests coverage is quite limited in terms of functionality due to the high dependency on the platform's capabilities. There are a few tests to check the IDL correctness and some basic spec conformance. https://wpt.fyi/results/html/editing/editing-0/autocorrection/autocorrection.html?label=experimental&label=master&aligned https://github.com/web-platform-tests/wpt/blob/master/html/editing/editing-0/autocorrection/autocorrect-off-touch-keyboard-manual.html
The HTML autocorrect attribute allows web authors to control whether autocorrection should be applied to user input in editable elements including <input>, <textarea>, and contenteditable hosts. The feature makes the 'autocorrect' attribute to be exposed to web authors.
The 'autocorrect' HTML attribute has been implemented long ago, but since it's not defined in any exported IDL, websites fail to detected it as supported.
Samples: https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Global_attributes/autocorrect#examples