The random insertion location of UUID4 causes bloat (at least index bloat) as it forces splitting leaves in order to add new entries, so you end up with a lot m

The random insertion location of UUID4 causes bloat (at least index bloat) as it forces splitting leaves in order to add new entries, so you end up with a lot more partial leaves: with sequential insertion (sequences, uuid7) the leaves get filled and when a leaf is filled you append a new one, you don’t go and revisit leaves.