[Experiment] Clicking “Sign In/Sign Up for Alerts” buttons from the main page with a random string entered in the email field, wrongly transfers the string to “Sign in” page

[heres-maria-sv-inactive]

[Notes]:

• If the email field from the main page remains empty and the “Sign in” button is pressed, the “Sign in” page wrongly displays the invalid email error as if you tried to submit the empty field
• After the steps below are executed, navigating to a breach from the “Breaches” page and clicking the “Sign in” or “Sign Up for Alerts” page buttons also transfers the string initially entered in the main page.

[Affected Versions]:

• Firefox Beta Build ID 20200309155231
• Chrome 80.0.3987.149
• Firefox (Fennec) 68.6.0

[Affected Platforms]:

• Windows 10 (x64)
• Android 9 - Samsung Galaxy S8

[Prerequisites]:

• You are on the Monitor mainpage, on any branch.
• You have not performed a breach search, nor have you signed into an account until now.

[Steps to reproduce]:

1. Enter a random string, not a valid email, in the email text field.
2. Click the "Sign In" button from the header.
3. After being redirected to the “Sign in” page, observe the email field.

[Expected results]:

• The email field is empty, the entered string is not transferred.

[Actual results]:

• The email field is wrongly populated with the string entered in the main page email field.

[Additional Notes]:

• Attached is a recording of the issue.
  

[heres-maria-sv-inactive]

I have verified that this issue is no longer reproducible using Firefox Beta 75.0b1 Build ID 20200309155231 on Windows 10 (x64), Firefox 23 on iOS 13.3.1 (iPhone 7+), as well as Firefox 68.6.0 on Android 10 (Motorola One Vision).
The content of the email text field is no longer remembered for any of the sign-ins.
As a result, I am closing this issue.