Hi @onuraydinay, @Jonasz-
Our team was able to find a workaround for this change introduced by Unity. The SDK update will require a few more steps (specifically to ensure MRAID works) and will not make it to the upcoming 4.15 release. It will be a hotfix following the 4.15 update later this month (tentative ETA EOMonth).
Until then we commend you to revert back to a Unity version below 5.6 for their Android apps to ensure that the banners work as expected.