Here we go .....
told you so.:-).
UK CAA has published and updated their website regularly regarding the effects of Brexit and anyone with still a UK license now complaining that EASA is not recognising their license......tough luck.
The reason EASA pilots can fly a G-reg in the UK is (correct me if I'm worng) the 2 out of 3 rule.
G-reg in G country with a foreign but recognised license, 2 out of 3 so it's legal since.
Flying a EI-reg heli in Ireland with your UK license is to my knowledge not allowed since the license you have is for EASA worth nothing, so 2 out of 3 doesn't apply since there is no nr. 3.
(Country, Reg, License)