When attempting to view a Donorbox popup form on a mobile device, you will be directed to the Donorbox-hosted donation page. This is because popup windows do not render properly on a mobile screen. Your donation form may get cut off and the donor experience would not be good, which is not ideal for someone who wants to donate.
In Donorbox, we always strive to give donors and organizations a better user experience. So, redirecting the link to the Donorbox-hosted donations page is a better solution. It also has the added bonus of allowing donors to donate via Apple Pay (not available on embedded forms).