Ah! This #KSK rollover is delayed because the manufacturer of the #HSM used by IANA (and Verisign) for the KSK management will cease production of the devices used
"There is a strong likelihood we will seek to generate a new KSK on a new HSM platform once operationalized, which will cause us to abandon the recently generated KSK"
https://mm.icann.org/pipermail/root-dnssec-announce/2023/000160.html