I might be one of those victims! I originally got my ATPL theory credit through a combination of a few EASA exams and military exemptions. This satisfied EASA's ATPL theoretical knowledge prior to Brexit. Under the above scheme, do you think someone like Malta would still insist on seeing 14 exam passes despite an individual already holding an ATPL that was fully EASA compliant until last year?
I am in a similar position, my UK issued ATPLH is up to date with a valid type rating (issued in Finland this year) - it seems that Malta would accept this and allow me to transfer my licence to their nation and let me fly EU registered aircraft.