After upgrade to MW 1.43 the $wgCaptchaClass must be defined with the full namespace:
in my case $wgCaptchaClass = 'ReCaptchaNoCaptcha'; must be:
$wgCaptchaClass = 'MediaWiki\\Extension\\ConfirmEdit\\ReCaptchaNoCaptcha\\ReCaptchaNoCaptcha';
if not doing this I have stack that says that class isn't definied.
other users have this problem:
https://www.mediawiki.org/wiki/Extension_talk:ConfirmEdit
Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
MediaWiki 1.43.3
PHP 8.3.21 (fpm-fcgi)
ICU 70.1
MySQL 5.7.44-48-log
Other information (browser name/version, screenshots, etc.):
Chrome Version 137.0.7151.122 (Official Build) (64-bit)