There is a way to avoid restrictions relating to a browser native subscription popup.
A native subscription popup can be shown to a particular user only twice. If a user doesn’t allow push notifications and closes the native subscription popup two times in a row, it won’t be shown again and push notifications are considered blocked.
A Custom Subscription Popup,
which can be implemented via Pushwoosh SDK, can be displayed as many times as needed unless a user subscribes to or blocks push notifications explicitly.