It's been a few years since I've been involved in this sort of stuff, but to me it looks like a high-volume service that is sending out bitcoin (e.g. an exchange or casino). If I wasn't so lazy, looking at the time the transactions were propagated would help figure out what's going on.


Most coinselection algorithms (including bitcoin cores) are kind of designed for user-level wallets, so they are massively consolidatory in regards to wallet utxos. This naturally means when you start sending out a lot of transactions, you're going to often generate huge unconfirmed transaction chains. This easily results in problems because of the mempool limitations (e.g maxdepth type thing).

With bustabit, I spent a few months and wrote my own purpose-built coinselection system to avoid these problems, but for most people that's a lot too much work and it's easier to just do a hack like make transactions occasionally include multiple-change outputs. That would likely explain some of the of the DAG like graphs you see?