We have applications where we control the creation of the primary key, and where the primary key will be exposed to end users, such as when using a typical web app framework built with Rails, Phoenix, Loco, Laravel, etc. For these applications, UUIDv7 time is too problematic for security, so we prefer binary-stored UUIDv4 even though it's less efficient.

We also have applications where we control the creation of the primary key, and where we can ensure the primary key is never shown to users. For these applications, UUIDv7 is slower at inserts and joins, so we prefer BIGSERIAL for primary key, and binary-stored UUIDv4 for showing to users such as in URLs.