The key seems to be based on UUIDv7, starting with a timestamp in milliseconds. So the order can become out of sync if multiple events happen in the same milli

The key seems to be based on UUIDv7, starting with a timestamp in milliseconds. So the order can become out of sync if multiple events happen in the same millisecond; or if your servers' clock error is greater than a millisecond (i.e. if you're an NTP user) More than sufficient for things like ordering tweets. If you're ordering bank account transactions, well, you'd probably be using transactions in an ACID-compliant relational database.