I don’t have any insider info, but it seems like they had to outsource deposit/withdrawal functionality to a third-party due to regulations, and it seems like that third-party happens to not support Lightning. I don’t know if the lack of support is for regulatory reasons or just not a business priority.
Ok, so in Germany it's not a third party using Kraken systems as a whitelabel, but a completely different system?
I have no concrete knowledge but that seems to be implied based on public information
Btw, also finex and Okcoin dropped support for LN in Germany, so this seems to be regulatory in nature.