I've done a bunch of bookings on the week before the 14/11 change. I trust these aren't going to have changed in the past week:

1. CX.com cash purchase*: allowed to input partner FFP before payment https://www.facebook.com/share/p/15PpJYBFTCy/?
(Edited 21:11) 2. Cathay redemptions*: allowed to input partner FFP before finalisation of redemption, see P.S. below.
(*Edit 22:26 - also applies to phone cash purchase and redemptions https://www.flyertalk.com/forum/37445590-post167.html )

3. QR Avios redemption: allowed to input partner FFP before finalisation of redemption QR charging seat selection fees in J (incl redemptions) like BA w/c 3 Nov 2025 (just checked - this can be selected for redemptions on CX too)

Data points further back (these may be stale):

4/11:
4. CX sector issued by another airline (CI, as protection for a cancellation of theirs): CI can't change it. CX Tsuen Wan added my and my wife's FFPs back with two attempts.

Mid-Oct:
5. BA redemption: Now this is on QF sector rather than CX, but BA wasn't pushing back when I added FFP with them as ticket issuer, rather than having to go to QF as flight operator.

Mid-Jun:
6. Non-online TAs: can still add (or at least remove) FFPs Changing FFP# [2025]

Edit 21:11: actually with Cathay redemptions there’s an option to enter FFP if redeemed online? See below. Just that perhaps until recent crackdown, we’ve never really had to use it: