Yes, sorry, L1 = Layer 1
Bitcoin has L2s (Layer 2s) that purport to fully replace Monero. But this is simply not true. Moving into L2 comes with it's own set of trade-offs.
For example - LiquidBTC, Fedimints, and Ecash all offer privacy on a layer above bitcoin (L2+), but you give up custody to gain that privacy. A critical pillar of bitcoin is self-custody. You can keep both with Monero.
Monero is not an L2 on Bitcoin. It's a completely different crypto from Bitcoin to be clear.