As Cargo Flights Leave Kaliningrad, Air Defence Systems Disappear
https://www.bellingcat.com/news/2023/11/13/as-cargo-flights-leave-kaliningrad-air-defence-systems-disappear/
“From this [ low-res ] imagery, it appears plausible that air defence systems at locations A (northern battery) and B may account for at least some of the increase in heavy military cargo flights going in and out of Kaliningrad.
“However, this can not be determined for certain and the contents of these flights cannot be determined without additional information.”
In short, the AD systems may or may not have disappeared/moved. Evidence inconclusive.
“As Cargo Flights Leave Kaliningrad”
Previously, ground combat units based in Kaliningrad have been rotated to the Ukraine (and chewed up badly).
Because Kaliningrad is surrounded, any war plan would have to prepare for a siege, with stockpiled supplies. I would not be surprised (kind of expect) that they have to tap a lot of those stockpiles now, for all sorts of shortages in the Ukraine. Artillery shell resupply could require a lot of airlift, but they are probably pulling everything they need.
Maybe the losses in Avdiivka caused them to suddenly accept more risk in Kaliningrad, or maybe availability of essential supplies and equipment got so low, that it just reached Kaliningrad on the priority list. They probably have to pull their horns in and accept risk everywhere, to keep such a flow of hardware and supplies into the Ukrainian meatgrinder.
The two S-400s they indicated (as possibly pulled from Kaliningrad) looked like backups/second layer,, behind the ones around the border, so they would not be sacrificing any blind spots in coverage.
They seem to be the rational ones to pull, if you have to accept more risk.