I also think that this is the most data waiting for confirmation so far, but not the most blocks worth of transactions waiting. In January 2018 we had a depth of 331 blocks, now it’s only 245 so far (but the blocks are bigger now).

I don’t know if we will ever see an empty mempool again or not. If Inscriptions remain popular, we might always have a backlog going forth. We might even if Inscriptions don’t. Or maybe it will clear again. It did briefly clear on the 26th of February, well into the Inscription hype.