I have been using the 1.21B01 Hotfix which it fixes the KrØØk vulnerability in the DIR-880L.
I have been using this Hotfix for a couple of weeks, and it works flawlessly from my standpoint.
Support for the 880L ends tomorrow (August 8, 2020), so it's the latest update unless D-Link uploads new firmware tonight or tomorrow.
I like this router a lot and I will continue using it until a serious vulnerable with its continued use becomes reported.
Mark