I bought mine directly from Samsung, pre-ordering it after the "Unpacked" event in August.
It came with the July 2021 security patch. It's now September 24th and still nothing here in the UK unless you own a budget A52 or similar, in which case you have the update already. The whole point of delivering security patches independently of other items without the need for operator approval was specifically so that people aren't left vulnerable because their network operator can't be bothered to approve updates (they would much rather you order a new phone than support existing devices).
It's not network operators holding this up, it's Samsung not releasing it to the Z-Fold3 in most regions for some reason.
