It seems to be similar to the 8 monthly free drops for Genshin Impact from Prime Gaming. A small treat for Amazon subscribers.
Item(s) included in Bundle #1:
Stellar Jade (60)
Credit (40,000)
Refined Aether (5)
And expires dates for all 8 drops.
Redemption Code from drop #1 expires on 21 Jun 2023 - 23:59 (UTC+8)
Redemption Code from drop #2 expires on 12 Jul 2023 - 23:59 (UTC+8)
Redemption Code from drop #3 expires on 2 Aug 2023 - 23:59 (UTC+8)
Redemption Code from drop #4 expires on 23 Aug 2023 - 23:59 (UTC+8)
Redemption Code from drop #5 expires on 13 Sep 2023 - 23:59 (UTC+8)
Redemption Code from drop #6 expires on 4 Oct 2023 - 23:59 (UTC+8)
Redemption Code from drop #7 expires on 25 Oct 2023 - 23:59 (UTC+8)
Redemption Code from drop #8 expires on 15 Nov 2023 - 23:59 (UTC+8)
Wished there was a bonus aesthetic reward for collecting all 8 of them like in Genshin Impact.