UI/UX: Auth form animation is not smooth when switching from Sign Up to Sign In

[IntrosWorld]

Description

The authentication form on the login page shows inconsistent animation behavior when toggling between Sign In and Sign Up modes.

Current Behavior

1. When clicking "Sign Up" button, the form expands smoothly to show the "Full Name" field
2. When clicking "Sign In" button again, the "Full Name" field disappears instantly without animation

This creates a jarring user experience with inconsistent transitions.

Expected Behavior

Both transitions (Sign In → Sign Up and Sign Up → Sign In) should have smooth, consistent animations with the same duration and easing.

Steps to Reproduce

1. Navigate to the sign in/signup page
2. Click on "Sign Up" button - observe smooth expansion
3. Click on "Sign In" button - observe instant collapse (no animation)

issue1.mp4

[IntrosWorld]

@whatsupsumit can I work on this ?