there's also one more obvious detail I should note for the sake of the graph – blob fees are relatively low at the moment, so the cost per transaction decreases as more transactions are handled, and given base is one of the most used L2s, that essentially flatlines their gas used on L1 per L2 tx. Other L2s with significantly more variable but lower usage also using blobs (OP, for example) will register as more costly on the graph.

There are so many insanely smart ppl in this ecosystem. 

I'm eternally grateful for this cozy corner where anyone can get simplified answers to confusing data-fueled questions within minutes of asking.