Why is secure_customer_sig getting removed from my app?

Hi We are trying to install an App via Shipify Apps, and we were told by the App developers the following:

Can anyone please help or advice what to do?

Message from the App developers:

As per our analysis, the following cookie - secure_customer_sig is getting removed through some event, due to which the customer will be logged out of their account automatically from your Store.

Hello!

Were you able to identify the issue? If yes, what was causing it?