Ethereum

L2s can't have real privacy if L1 doesn't have privacy.

Since rollups' security properties requires the ability for an L1 user to force inclusion of a transaction in a rollup, then true L2 privacy only exists if there is a way to do force-inclusion without revealing the identity of the L1 or L2 user in the process.

but force inclusion in the privacy zk rollups context would mean publishing a  proof. . . the inputs can remain private

you still need 'clean eth' to pay for gas for the force inclusion. . . one of the few advantages of POW over POS, you can privately generate gas.