That's all true, but this seems disproportionate even to the hardware market. They already raised their prices recently as hardware got more expensive, and now they are quadrupled. Maybe I am just misreading the hardware market right now.
If you see photos/videos of Hetzner datacenters, their servers are essentially plain, low-end motherboards (1G network, few slots) sitting on shelves (don't mean that as derogatory, it's an efficient design). What it does mean is that their per-server costs are absolutely dominated by the very components that are exploding in cost right now: RAM, SSDs and (to a lesser extent) CPUs.