PFsense Plus 23.09 has been released
Releases — 23.09 New Features and Changes | pfSense Documentation (netgate.com)
23.05.1 is giving me the option to upgrade. 
Do I dare? Or wait for 2.7.1 or 2.8.0 CE to switch off plus then?
Snap ! Though I think I will wait until the weekend to see what happens on updating.
I ran into a minor issue with switching to the kea-dhcp server. My Service Watchdog tried to restart the old service, but it obviously failed.
Also, the Auto Config Backup was failing, but a restart solved the problem.
Seems Netgate “fixed” the issue offering upgrades from 23.05.1 to 23.09 for previous valid plus license holders. I’ve already converted one system back to 2.7.0 CE. 1 down, 2 more to go.
I realised that I had my backup box lying around to be actually configured as the backup.
It had a registered version of PfSense plus 23.05.1 installed, was able to upgrade this to 23.09 without any issues.
My main box is running 23.05.1 which still shows the option to upgrade to 23.09.
I suspect over time they will turn the tap off.
I just updated mine to 23.09, took quite some time to come back online as well. Haven’t bought a TAC license yet so I was surprised it let me update.
Updated my home/lab which is just a recycled mini PC, without issues from 23.05.1 (running PFblockerNG and Snort). Had used the discounted offer - about £82.00 over my side of the pond - but now feeling a bit foolish for doing so at the same time as ‘well, I’ve supported the work they do’…