The only inventory management(IM) risk when you provide liquidity on rETH/ETH is the gas fee to refuel your L2 position(Withdraw from L2, Swap/deposit on Rocketpool (r)ETH, deposit on L2 again).
There is also an opportunity risk, if your spread is less than the yield you would have if you simply hold rETH.
There is no IM risk of being offline (low volatility).
The two major risks are ZKsync smart contracts(bridge, validity proof), and of course my bot implementation.
gas fees won’t drop after the merge. The reason that everything will get cheaper on ethereum will be due to utilizing sharding via shard chains. Those chains are looking to use ZKroll-ups, which will allow cheaper fees on L2, because it can aggregate a LOT of transactions into a single transaction/validation on L1 after the merge.