I mentioned this on Github as well, but since there’s hardly any activity from support/devs I’ll post it here as well.
The dashicons font family is overridden on the login page because of an !important, in inline css, generated by user settings and thus shown as a tofu.
You see a tofu circled in red. An ‘eye’ dashicon would need to show there.
Remove the important
$i from line 110 in src/includes/classes/login-customizations.inc.php
This only happens after saving the user settings. If not saved, default settings are used, which do not have this (css) line.