App getting rejection because of 3rd party cookies

[somin]

@Shopify 

Greeting ...!
Our app is getting rejection during the review.
The reason given is 'Embedded apps that rely on 3rd party cookies are prohibited from the Shopify App Store. Implement sessions tokens to embed your app.'
As far as we know, our app does not using any 3rd party cookie.
Even in the video given with the rejection mail, we could not find proper explanation about the issue.
We have searched it from our side but we could not find anything regarding that.
We are unable to get the exact issue why the app is getting rejection.

It would be grateful for us if anyone have some idea how to fix this issue ?
Thanks in Advance.