I’ve created a b2c signup flow through custom policy and the user journey is working fine. But, while clicking the ‘Signup’ icon there is a bit ‘flicker’ with a message displaying as ‘what is this?’, On the side of each field while loading a complete registration page. For better user experience, is there any customization required for b2c html or in a custom policy to override this behavior. I’m assuming this may be a b2c-html late loading style sheet.
Assuming you're customising the UI with your own HTML page templates then try adding a data-preload="true" attribute to your CSS (and JS).
If that still doesn't work then I'd recommend setting your HTML page template body content to be hidden by default, B2C should then automatically unhide it when page load is complete but if it doesn't you can use JS to unhide it yourself on document ready.