[2023] Warcry's cold inc% damage node(frost claw) is not working

The node is working. It is just applying the buff after casting the stacks of Maelstrom, and the stacks of Maelstrom don’t update their damage dynamically, so a buff granted after casting it doesn’t apply to the old stacks.

You do, but not for the stacks of Maelstrom already cast or cast by that Warcry, but any Maelstroms stacks gain after getting the buff will get affected. It’s sadly just how the system works and we don’t have a way to change it at the moment.