Given this apparent change in deadline for initiating registration, and the general lag in ACP homologation, it might make relying on late May/early June qualifiers somewhat risky?
What is this "general lag in ACP homologations"? Do you know something others don't - at least as far as UK is concerned? Audax UK make strenuous efforts to get results turned from provisional to 'with homologations' swiftly and, so far in 2023 this has been achieved (as it was with a flourish in 2019). Full entry set at €190. https://www.paris-brest-paris.org/en/rules/
I don't think it's controversial to suggest it takes longer for a BRM to be validated (up to and including communication of ACP homologation number) than a BR? For instance, as it stands today I have no idea what the homologation number of a BRM I did on 4th March is, and that's not a knock on the organiser, AUK or ACP, who I'm sure are all moving as quickly as possible. But equally, on a similar timetable later in the year, I could not rely on being able to use a BRM completed on 1st June to satisfy this updated "3 completed qualifiiers on the registration by 10th June" condition as it would require knowing the homologation number of the ride.
Edited to add:
The AUK BRM qualifying windows (below) appeared to take cognisance of the ACP cutoffs. So 400 qualifiers ceasing 10 days (to allow time for homologation?) before the ACP's previous registration commencement deadline of the 20th, and similarly 600 qualifiers to be completed by weekend of 24th June, a week before ACP registration final deadline of 2nd July. The ACP move appears to break the first of those, somewhat.
200k: Sat 7 Jan - Sun 30 Apr
300k: Sat 11 Mar - Sun 21 May
400k: Sun 9 Apr - Sat 10 Jun
600k: Sat 6 May - Sat 24 June