Re-upping my post from 1.5 years ago on "layer 3s":

https://vitalik.eth.limo/general/2022/09/17/layer_3.html

The summary is that layer 3s don't magically improve throughput even more, though they can reduce some fixed costs of batch publishing and deposits/withdrawals.

Just read the article on Polygon Lab founder Marc Boiron perspective on L1’s. He argues If all L3s consolidate into a single L2, Ethereum could lose its value, posing a security risk. Does the existence of (L3) networks, absorb Ethereum's value. Why would more L2’s pose a security risk. I’m puzzled.