How to calculate tax on rollups (L2s)

Gm everyone! I was wondering if any of you can help me on how crypto tax is calculated on L2s. For L1, I calculated everything using FIFO method. 1. Is bridging taxable event? 2. How are realized and unrealized gains calculated? If I spend some ETH on L2, do I need to know its origin and calculate gains based on that info? For more information: Let’s say I earned 1 ETH on L1, when price was $1000, and for sake of simple calculations, let’s say that there are no gas fees. If I bridge that 1 ETH to Optimism, when price is $1500, did I trigger a taxable event, in which case I realized gain of $500? Later, if I spend that whole ETH, when price is $3000, did I realize a gain of $2000 (sell price $3000 - origin price $1000), or $1500 (sell price $3000 - price at the time of bridging $1500, in case bridging is taxable and bridged tokens are looked as received), or something else? Thanks ????