Additionally I forgot to mention that I found out during some researches that this optimisation currently seems usable on the Base network too: Fees | Base
Regarding Polygon zkEVM this also seems possible as stated in this doc, the L2 fee is mostly a portion of the L1 fee: Astar zkEVM Fee Calculation | Astar Docs
Edit: after trying this on Polygon zkEVM, it doesn’t seem the same calculation ways.
More testing in real conditions will be required to find out exactly the conditions of fee savings for these layers.
But this looks very promising as it would be applied on 3 layers where Paraswap is deployed!