Moved topic out of CBSubs support as issue does appear to have anything to do with CBSubs. As for your issue that should already be just working out of the box if you're on Joomla 4. I don't recall if Joomla 3 has this out of the box, but by now everyone should have or should be making the move to Joomla 4 as Joomla 3 support ends next month and you risk your site becoming a security problem. Below is CBs login module on Joomla 4.
Password Hidden
Password Visible
The eyeball icon toggles password visibility.