yeah, the current typical spend and change pattern is terrible for privacy though

IMO, the change should create several randomly sized progressively smaller units out of the change side and then in the future spends can clear out a set of them, picking the oldest ones to decrease correlation, and merging them to the new UTXO

i use coin control interface on bitcoin core and i like how it lets me pick out which to use and i generally try to spend the oldest ones first, and i've started to sometimes create my own change addresses manually, but i think they should be broken up into several pieces by default then often i just pick out a set of old ones that get close to my desired spend and only one has to be split after that

i mean, there's probably various models for this, where you can configure a model to optimize by some bias towards small transactions or bigger ones, and this could be automatically prompted by the mempool fee rate curve, so it prefers to break a big one into two when fees are high, or spend old, close to exact sum smaller ones when fees are low

improving the privacy of wallets probably there is many ways to make this work even better

lightning and Ark also hint at some interesting ways that we could increase privacy with other people in a more automatic way, especially with the help of a social graph like nostr