How UUID v7 is structured
UUID v7 contains a 48-bit Unix timestamp in milliseconds, version and variant bits, and a 74-bit random field. Each batch starts with a securely generated random value and increments that field to preserve order within the batch. Order across batches and monotonicity when the clock moves backward are not guaranteed.
Privacy and uniqueness
The timestamp reveals approximate creation time; use v4 when that is undesirable. Custom time does not make the complete result deterministic. Database uniqueness constraints are still needed